DOCUMENT RESUME

ED 057 250 VT 014 417

AUTHOR Stokes, Vernon L.TITLE An Instructional Program for Training Nondestructive

Testing and Inspection Technicians.YNSTITUTION North Texas State Univ., Denton.; Texas Education

Agency, Austin. Dept. of Occupational and TechnicalEducation.

PUB DATE Aug 71NOTE 199p.

EDRS PRICE MF-$0.65 HC-$6.58DEScRIPTORS Bibliographies; Community Colleges; *Curriculum

Guides; *Industrial Education; Inspection;Instructional Materials; Instructional Programs;Junior Colleges; Manufacturing Industry; *ProductionTechnicians; Program Content; Resource Materials;*Supplementary Textbooks; *Technical Education

IDENTIFIERS Nondestructive Testing

ABSTRAcTThis document, the second portion of a two-part

study, is designed to provide a guide for the formal training oftechnicians for nondestructive testing and inspection. Information inthe guide is based on results of the industrial survey discussed inPart I. The subject matter is intended to be both flexible andcomprehensive, and instructional goals must be focused on attainmentof a high level of proficiency in each technician. This documentcontains an introduction consisting of considerations forinstruction, significance of the manufacturing process,responsibility of the manufacturer and service company, and educationobjectives. Also, there are chapters on: (1) The Origin andSignifLcance of Discontinuities, (2) Liquid Penetrant Methods, (3)Magnetic Particle Testing, (4) Eddy Curre-°- ig, (5) UltrasonicTesting, (6) Radiographic Testing, (7) .tstructive TestingMethods, and (8) Curriculum. Sample illustrations and resourcematerials are appended, and a bibliography is included. Part I isavailable as VT 014 416. (GET)

n AN INSTRUCT I ONAL PROGRAM

FOR TRAIN 1 NG

NONDESTRUCTIVE TESTI NG

AND

INSPECTION TECHNICIANS

Texas Education Agency

1

U.S. DEPARTMENT OF HEALTH,EDUCATION SI WELFAREOFFICE OF EDUCATION

THIS DOCUMENT HAS BEEN REPRO-DUCED EXACTLY AS RECEIVED FROMTHE PERSON OR ORGANIZATION ORIG-INATING IT. POINTS OF VIEW OR OPIN-IONS STATED DO NOT NecEssARILYREPRESENT OFFICIAL OFFICE OF EDU-CATION POSITION OR POLICY

AN INSTRUCTIONAL PROGRAM FOR TRAINING

NONDESTRUCTIVE TESTING AND

INSPECTION TECHNICIANS

By

Vernon L. StokesPrincipal Investigator

Dr. William A. MillerProject Director

Denton, Texas

August, 1971

FOREWORD

This research project was conducted under the direction

of North Texas State University in cooperation with the

Division of Occupational Research and Development, Texas

Education Agency.

The study is composed of two parts:

A Study, of Nondestructive Testing and Inspection

Processes Used in Industry with Implications for Program

Planning in the Junior Colleges of Texas

An Instrl cional Program for Training Nondestructive

Testing and Inspection Technicians

3ii

TABLE OF CONTENTS

Chapter

Page

I. INTRODUCTION 1

An Introduction to Nondestructive TestingConsiderations for IriructionSignificance of the Manuf. ,turing ProcessResponsibility of the Manufacturer and

Service CompanyEducational Objectives

II. THE ORIGIN AND SIGNIFICANCE OP DISCONTINUITIES 9

Metal ProductionThe Discontinuity in the IngotShapes of DiscontinuitiesDiscontinuity in the WeldObjectivesOutline of Key Points

III. LIQ,UID PENETRANT METHOD 29

Testi'. nspection TeLA-IniquesUleaning ()I PartEquipmentEvaluationSafety PrecautionsObjectivesOutline of Key Points

Iv. MAGNETIC PARTICLE TESTING14-3

Principles of TestingCircular FieldLongitudinal FieldPolar EnvironmentsCurrent UseInspection TechniquesEquipmentEValuationtemagnetizationSafety PrecautionsObjectivesOutline of Key Points

iii

V. EDDY CURRENT TESTING

Page

63

Principles of the TestTesting TechniquesTypes of TestsNeed for ReferencesEddy Current CharacteristicsEddy Current in AutomationSafety PrecautionsObjectivesOutline of Key Points

VI, ULTRASONIC TESTING 82

Principles of the TestTesting TechniquesSignal CharacteristicsThe Search.ProcessSafety PrecautionsObjectivesOutline of Key Points

VII. RADIOGRAPHIC TESTING

Characteristics of RadiationTechniques in RadiographyPrecautions in RadiographyEmission of Penetrating Rays of EnergyRay MeasurementsDetermine the Source NeedObjectivesOutline of Key Points

VIII. OTHER NONDESTRUCTIVE TESTING METHODS 118

Magnetic Rubber TestInfrared TestAcoustic EmIssion TestOther Techniques Used in Nondestructive Testing

IX. CURRICULUM 122

Proposed Curriculum in Nondestructive TestingCourses of Instruction

PEND1X 137

BLIOGRAPHY 185

iv

CHAPTER I

INTRODUCTION

The purpose of this instructional program is to provide

a guide for the formal training of nondestructive testing

and inspection technicians. Information contained in this

guide is based on results of an industrial survey wh5ch is

described in Part I of thi.E, study.

An Introduction to Nondestructive Testing

Because nondestructive testing involves the use of many

forms of energy and reaches into most types of industrial

occupations, the testing procedures shown in this training

guide have been divided, due to this enormity, into five main

methods of testing. Proficiency in the application of these-

five testina lethods will enable tne technician to test and

inspect all kinds and shapes of manufactured parts and assem-

blies which are produced from the numerous manufacturing

processes. However, these main methods of testing do not give

a complete inspection coverage of tiles industrial field. There-

fore, several independent or supplementary type tests are

described in Chapter VIII.

The five main methods of nondestructive testinq include

liquid penetrant, magnetic particle, eddy current, ultra-

sonic, and radiographic processes. The descriptions of these

6

2

testing processes are ar7-anged in this guide so that each

process is introduced and reviewed separately. The intro-duction to the process is aimed primarily at acquaintin,..;

those concerned personnel with the general purposes, tech-

niques, and results of the testing method. The objectives ofeach test are then outlined in specific terms so that a highlevel of technician proficiency will be expected. The outlineof the proposed program which follows the objectives providesa guide for establishing key subject areas to be considered byinstructional personnel in formulation of each course syllabus.This outline is not arranged in a teaching sequence, butmerely reflects the general scope of needed subject matter to

be covered.

Conside-,ations for Instruction

The general subject matter outline of this proposedprogram is intended to be flexible and comprehensive. It

includes many of the key areas involved in the several test-ing, inspection, and evaluation techniques. Each of thesetesting and inspection subject areas should therefore be in-cluded in appropriate course syllabii and should be supportedwith a degree of emphasis that will enable the trainee tounderstand and be able to apply the basic principles of thespecific test. Obviously, several hours of concentrated

instruction will be required in each of the outlined items ofsubject matter in order to accomplish the objectives of theinstructional program. Further preparation for each specific

7

3

course should include teaching plans stemming from the course

syllabus. This type of plan is specific and relates to a

specific unit of learning. This is the step in the learning

process that seeks meaning in action.

Instructional methods must include a combination of

techniques that will enable the trainee, over an extendee

period of time, to attain those behavioral objectives which

are listed in subsequent chapters. The time required to attain

these objectives through training is equated in semester credit

hours and in turn into clock hours. For academdc credit pur-

poses, three semester hours of college credit will then re-

quire two clock hours of lecture and three clock hour,3 of

laboratory work for each three hour subject when the subject

is laboratory oriented. The lecture and laboratory efforts

of instruction will then aim at preparing the trainee to be

able to test, inspect, and evaluate the quality and degree of

reliability of typically manufactured parts and assemblies.

Examples of these typical parts and assemblies are listed in

Appendix A.

The goal of instruction is then to provide technical

capability in the trainee and process him ini.o a reliable

technician. Therefore, principles and other elements of

theory must be translated into elements of action. The

trainee must be provided with the instructional environ-ment that will allow him to "do" and be able to think aboutwhat and why he is "doing" it. Capability and dependability

LI-

constitute the foundation for technical proficiency. In

nondestructive testing, there is no room for guess and

possible error.

Because there is no one best method of instruction,

supervisors and instructors should direct their philosophies

toward quality in the end product. This quality factor

reflects from the industrial goal of near perfection in manu-

facture. A reliability factor of 100 per cent is justifiable

and stands as the ultimate factor when the safety of people

is concerned. As an example, in aircraft transportation, if

one flight becomes a disaster out of 100 flights, a dangerous

situation exists. In fact, the situation shows that personnel

responsible for the flight are lacking in some requirement.

An analysis of this situation could show inaccurate nondes-

tructive testing and evaluation techniques performed on the

aircraft. This analysis could be further focused on a critical

part that was evaluated as acceptable, but in reality, the part

was unacceptable. Just how this situation could have developed

depends on the total efficiency of the inspection team, rest-

ing heavily on the operator or technician. When human life

and high cost in money are concerned, a 100 per cent relia-

bility factor must be expected. Therefore, instructional

goals must be focused on attainment of a high level of pro-

ficiency in each technician. It is then estimated that at

least two academic sohool years will be required to effectively

complete the requirements of this program.

9

5

Significance of the Manufacturing Process

Prior to summarizing the main testing methods indicated

in this guide, a review of several manufacturing processes

will be accomplished. The purpose of this review is to por-

tray some of the processes used in manufacturing the part.

The manufacturing process tells the life history of the part

and is consequently considered vital in fina] evaluation.

To know the history of the part is to be able to accept or

reject the part at the end of the manufacturing process.

Acceptance or rejection rests heavily on inspection indica-

tions, part history, projected use of the part, and its future

environment. How the part was made helps to understand inspec-

tion results and in turn, provides a means for a more validevaluation.

There is a direct relationship between manufacturing

process and resultant flaws in the part. Flaws are unwantedand often become dangerous preas in the part. The flaw is

created during manufacture and often remains in the materialfor the life of the material. Flaws are accidental or in-cidental additions to homogeneous materials. The most

dangerous flaw is the discontinuity or material separation.This discontinuity frequently manifests itself in the shapeof a crack. The crack may or may not be open to the part's

surface and its existence may justify scrapping the part.

The flaw may be large, whereby the human eye can see it andon the other :hand, it may be microscopic in size. Either

10

type is material separation and consequently, justifies

inspection and evaluation. If the cracked part is to be

highly stressed, the chances are high that rejection is

expected.

Responsibility of the Marufacturer and Service Company

Two areas of industry are concerned with nondestructive

testing, the manufacturer and the service company. From the

manufacturer's point of view, the part reflects his efficiency;

therefore, he wants to be assured that his parts are made from

sound material, being free from cracks and other undesirable

flaws.. From the point of view of the service company, the

finished part, which has been in use, must be reevaluated toascertain its continued service. Therefore, the part must be

removed from its assembly and subjected to a complete inspec-

tion to verify the continued soundness of the material. This

inspection is necessary because after several months of use,the part may have developed cracks e.nd become unsound and

unacceptable.

Fatigue, a time-load-use factor, frequently induces atiny crack in a part. Then, over a period of time while

under heavy loads, the small material separation becomes

enlarged. If the small crack, due to service use, is not

recognized during the nondestructive test and is allowed to

remain in use, sudden failure rests ahead. Consequently, theservice company, an airline for example, periodically performs

the nondestructive test on its airplanes. Keep in mind that

lii

7

the original manufacturer had produced sound parts for the

airplane, but in use, unsoundness may have developed. The

nondestructive test is therefore vital to both the service

company and the manufacturer in order to provide a high level

of quality control in the part.

An example of maximum effort in the use of nondestructive

testing is displayed on the cover of this guide. The F-111

is a fine example of quality control at work. All methods

and techniques of nondestructive testing are applied in the

manufacture and service of this airplane.

Educational Objectives

The objectives of this nondestructive testing and

inspection training program are to provide skilled technicians

who will be able to help assure a high degree of quality con-

trol and part reliability in the manufacturing processes.

Part reliability through quality control depends on the tech-

nician's attainment of specific objectives which are outlined

in subsequent chapters for each of the major testing and

inspection methods.

The specific behavioral objective must include provision

for comprehension as well as for capability. Attainment of

educational objectives will be considered accomplished when

the trainee can effectively perform the several techniques

and tasks included in each of the major inspection processes.

The trainee must be able to routinely and effectively

test for discontinuities, inspect the indications, and evaluate

6

the findings. Evaluation, the end product of testing, mustthen be followed by sound logic in deciding either acceptancecr rejection of the part.

Another goal of this 1.2oposed program is attainment ofa high level of proficiency in the technician so that indus-trial qualification and certification can be effected.

Educational aims and related criteria outlined by the AmericanSociety for Nondestructive Testing (Recommended Practice No.SNT-TC-1A), should be reviewed prior to establishment of aprogram. In this respect, another fine source of educationalliterature is the Materials Evaluation magazine, published bythe Amorican Society for Nondestructive Testing.

In addition to the objectives listed in this guide,reference should be made to Part Thirty-one, Annual Book ofASTM Standards. The American Society for Testing and Materialsprovides detailed information in regard to nondestructive tests.Another source of helpful information can be formulated fromthe Metals Handbook, published by the American Society forMetals.

One precaution concerning evaluation is stated and mustbe realized by the inspection team. During the inspectionand evaluation of a part, some border line decisions inevaluation occur. It must not be considered inefficiency toconsult higher authority prior to final acceptance of a partwhen circumstances are not clearly defined.

13

CHAPTER II

THE ORIGIN AND SIGNIFICANCE OF DISCO_FINUITIES

A discontinuity is a break or separation in a material.

The separation is either an inherent flaw or some kind ofcrack. When the base material, metal for example, of a partis separated by nonmetallic particles (inclusions) or voids,

a discontinuity in the base metal exists. Because discontin-uities are material separations, the load carrying ability ofthe material is reduced. When this reduction in stress re-action within the material is lowered to a critical point,failure occurs. If the part is critical with respect tototal design, tragedy may result. Therefore, the manufac-turer and service company have established special proceduresto find discontinuities in order to prevent these material

failures.

Because the designer is constantly trying to use more ofa material's strength, the need to assure material capability

has increased in great proportions during the past decade.Man has increasingly insisted that sound materials be pro-vided for his vehicles, his structures, and his tools.

However, this insistence has not always provided flawlessmaterials. Due to the fact that unsound materlals are beingproduced, the manufacturer has been alerted and has takenaction to find these unwanted flaws. The search has been

9 14

10

nondestructive; consequently, the nondestructive test was

originated. The test indicates that discontinuities are

detected in such a manner that the material's physical,

chemical, and mechanical properties are not altered. Be-

cause metals occupy a major portion of parts produced by

American industry and because most of the nondestructive tests

are more relevant to metals than nonmetals, this guide is

primarily concerned with the inspection of metals. However,

several of the tests are equally applicable to the nonmetals.

Metal Production

During metal production and refinement, many flaws are

sometimes created within the new metal. Because these flaws

are often developed during and soon after the molten metal is

poured, they are inherent and often remain with the associated

areas of metal to its end of existence. These flaws, includ-

ing the discontinuity, take many shapes and forms. Foreign

materials, fOr example, similar to slags, are sometimes cap-

tured in the molten metal as it solidifies and before they

have an opportunity to float to the surface. These captured

inclusions will remain as many sided particles in the casting,

but will elongate into stringers when the casting (ingot) is

subsequently reheated and rolled into bars or other shapes.

Clacks and holes which formed during the solidification stage

also remain as metal separations even during subsequent shap-

ing operations. The separation does not always weld itself

while in the presence of high temperature and pressure during

16

1J.

the forming operation because an oxide coating rest., )etween

the two surfaces of metal.

Metals are produced in either the ,:ast shap= or n some

other shape produced from the casting. The cast_ng, )eing

produced first, is the result of liquid metal cocling within

a mold. As the liquid metal solidifies (especially in intri-

cate castings), some metallic droplets may soliri_Lfy ahead of

the stream of molten metal, possibly by splashing, and become

quickly covered with the input of the moving stream. Because

of this temperature differential, the outside surfacrs of these

partially solid droplets become cold shuts, and at the same

time, become discontinuities. In other words, two masses of

metal are held tightly together, but are not fused together.

The cold shut sometimes occurs in the area of thick and thin

sections of metal. The shape of these discontinuities is

more rounded than elongated and their dimensional changes are

smooth. Parts containing these discontinuities will not

transmit stress across the metallic separation and are there-

fore not used for high strength fittings. Seve2al types of

discontinuities ale illustrated in Appendix B.

The Discontinuity in the Ingot

Because an ingot (a casting) cools in an uneven way and

because of the high temperature involved, its very coarse

grain structure provides no directional properties. Due to

uneven cooling, inclusions and cold shuts sometimes become

enclosed within the solid metal and remain in their geometrical

is

positions unless forced into different shapes by subsequent

forming operations. As solidification proceeds, should hot

gas at the mold's walls force itself into the mushy metal

prior to solidification, blow holes or cavities will result

in the metal, being open to the surface. Should entrapped

gas leak towards the metal's surface prior to solidification,

tiny pin holes or rounded porosity holes will form. Some-

times, one area of metal may cool faster than another, causing

a stress concentration. Should this stress concentration

overcome the metal's strength at the moment of solidification,

tearing of the metal results. This tear is jagged in shape

as opposed to rounded edges of holes and cold shuts. Refer-

ence should again be made to Appendix B.

The tear, inclusion, or cold shut may be internal or

either flaw may be exposed to the surface. Because these

flaws are born as metal solidification occurs, they are then

part of the metal and are not fit for carrying heavy or

alternating loads. In nonstressed areas under static loads,

however, the flaw may sometimes be considered as not critical.

As stress lines, because of loads, contact the flaw, they

make a curved path around the flaw. This concentration of

curved stress movements around the flaw creates stress

raisers and concentration points for internal overload and

subsequent potential failure. Also, in the presence of alter-

nating loads, the discontinuity will increase in size, thereby

decreasing the cross sectional area of metal. Obviously,

17

13

when this area reduction occurs, failure can be expected

without further warning. These types of discontinuities

are usually highly signifioant. The stress pattern is illus-

trated in Appendix C.

Cast parts take their shape from the frozen liquid, an

ingot being a typical example. When liquid metal is poured

into the ingot mold, solidification first begins at the

bottom and sides of the mold due to the cooling effects of

the mold's walls. Solidification proceeds outwards from

these solid nuclei to the mold's center until all metal has

been transformed from liquid to solid. When the mold becomes

full, pouring ceases. Because hot metal requires more volume

of space than cooler metal, shrinkage occurs along with cool-

ing, primarily at thr3 top of the mold. As the last amount of

molten mebal begins to solidify, the top center portion (last

to contain liquid) may sometimes sink. In some types of

molds, this depressed area contains a connecting void deeper

into the center region of the metal. The total depressed

area including the void is known as "pipe." Because of this

pipe and in order to avoid the possibility of including more

discontinuities in future products stemming from the pipe,

the top section of the mold is cropped away. Hopefully, the

cropped off area contained all of the unwanted pipe, porosity,

and other undesirable discontinuities. The removal of ingot

tops precedes the rolling operation. Appendix D illustrateo

the discontinuity in the ingot. At this point, it mist be

18

1)4.

pointed out that all ingots do not contain the top depres-

sion and are therefore not cropped. Frequently, the design

of the mold helps allow for desired solidification in the

top portion of the mold.

Shapes of Discontinuities

After cooling, the ingot is reheated and then processed

into different shapes by one of the wrought processes. These

processes include rolling, pressing, forging, and extrusion.

If any discontinuities remain in the ingot, they are then

carried within the finished wrought shape because they are

part of the shape. However, the initial shape of the discon-

tinuity as it existed in the ingot is changed to conform with

the mechanical pressures during surface operations. As an

example, the cold shut, the inclusion, the hole, and the

crack are elongated or flattened by forces of the forging

hammer or the rolls of the mill, and are always present but

existing in their new shapes. The new shape is often thin

and flat or long and thin. Regardless of the shape, the

discontinuity _Ls a metal separation. Therefore, caution must

be exercised in judging the potential of these flaws. Refer

to Appendix E for illustrations of these types of discontin-

uities.

Depending on the type of wrought operation performed,

discontinuities therefore take different shapes. As an

example, if the ingot is rolled into plate and sheet stock,

the inclusion and other discontinuities are often flattened

19

15

into pancake shapes and act as laminations between sound

areas of metal. Parts subsequently manufactured which con-

tain these laminations are subject to failure if severely

stressed. When welded pipe, for example, is machine folded

into the rounded shape from sheet stock containing this lami-

nation, the pipe will also contain this discontinuity. Also,

pipe edges that are not properly fused dliring welding will

produce seams. The seam is a longitudinally shaped discontin-

uity open to the surface in which a layer of oxide prevents

the parent metal from fusing. Appendix F illustrates these

types of discontinuities. Again, stressed parts must not be

manufactured from metals containing discontinuities. In this

respect, it is not always possible to produce a metal that is

100 per cent sound. In order to determine the acceptable

limit of discontinuities, reference must be made to governing

specifications and standards pertaining to the particular

test. Should a flawless metal be required, however, it is

then often advantageous to inspect the large mass of metal

prior to forming and machining operations. The presence of

the discontinuity is then evaluated.

Other forming operations which produce bars from the ingot

have different effects on discontinuities. Because the bar is

more confined on all sides as it moves longitudinally through

the rolls, the discontinuity becomes elongated as a strin,-,er

in the direction of rolling. Should a seamless tube or other

extrusion be produced from this bar, the inherent stringer

would then become a discontinuity in the tube, either runninE.

20

parallel to the direction of extrusion or rolling and exist-

ino along the axis of the tube or following the surface

contour in the form of a helix due to roll effects. The dis-

continuity which is open to the surface as a result of the

extrusion process takes the shape of a seam and must not be

used to carry loads. Stress will not cross the metal's epara-

tion at the seam; therefore, a satisfactory stress reaction to

an applied load will not occur. Consequently, the load, having

an inadequate reaction from the metal at a critical point

produces quick failure. If the ruptured part is arranged in

some type of "domino" design in the assembly, chain reaction

will often follow until complete failure of the assembly

results.

During the process of forming smaller shapes from the

ingot, other types of cracks often occur. Some cracks become

open to the surface and then remain as seams during continued

rolling or other wrought type of operations. Cracks are also

formed from sound metal during heat treatment. This type of

crack may run in any direction and may move across the grain

(intragranular) or along the grain boundaries (intergranular).

Also, this type of crack will remain as an internal discontin-

uity and may relieve the surrounding areas of stress by moving

to the surface. When metal is hardened by heating and quench-

ing, this type of heat treating crack will sometimes occur.

The crack may be deep within the metal or it may be open to

the surface. The crack results due to the inability of the

21

17

hardened metal to flow with the pressure of the inbernal

stress. In other words, hardened metal is stiff metal and

will not bend or flow an appreciable amount. The ductility

factor is low while the hardness factor is high. Due to a

sudden concentration of stress at a point of high resist-

ance, metal separation will occur as a crack when the stress

is greater than the metal's strength. Appendix F also

illustrates these cracks.

Metals that are subject to changing loads may also

initiate very small separations in the metal, often along

the edges. Continued stress variation, especially from tension

to compression in cyclic patterns, elongates the initially small

separation into a dangerous fatigue crack. As the crack reduces

the effective cross sectional area of the part, failure ap-

proaches, and at the critical moment, when no safety factor

remains, failure'occurs without warning. Cracks beginning

at the surfaces of materials often lead to fatigue failure.

Use of tha part must then be known in order to understand the

strength pattern. Parts manufactured from materials that

subsequently function in cyclic 1oad1ng patterns must be

sound throughout the cross section. The surface crack Is

especially dangerous when the part is used in alternating

loading cycles. The nondestructive test must be especially

aimed at this type of discontinuity. Appendix G illustrates

this discontinuity.

Machining operations often leave indented areas and

marks on the surface of the part. In effect, these are not

22

18

discontinuities, but are sometimes points where stress may

concentrate. The machine mark must therefore be evaluated

in terms of its significance to the stress pattern. Also,

when the part's design calls for.abrupt change in direction

or dimension, conditions prevail for potential stress concen-

tration and possible failures either through heat treating

cracks or stress overload. The designer must therefore

consider this stress condition during the design process.

Another source of cracks results from improper grinding

techniques during finishing operations. When too much pres-

sure is placed on the grinding wheel, the metal's surface will

overheat and often check into numerous tiny cracks. These

small cracks develop in a pattern which is across the direc-

tion of grinding wheel rotation. Depending on the use of the

part, checks may or may not be harmful. Highly stressed

parts however, must not include any types of cracks or other

discontinuities. Checked areas in a ground part are illus-

trated in Appendix H.

Sections of metal which are exposei to forging operations

may often contain discont'aluities. The lap is a typical exam-

ple. The lap is a thin area of metal which has been lapped

over the metalls surface and then folded bpck onto the surface

by means of the forging hammer. The folded metal is subsequent-

ly hammered into the surface. The lap is a discontinuity

because oxide coatings along the edges of the lap prevenC fusion

of the metal while hot. Also during forging, metal may burst

23

internally and form cracks and voids as the result of excessive

pressure while the metal is underheated, being much too cold.

These cracks become discontinuities. The burst may also ex-

tend to the surface. This type of crack is consequently the

beginning of further cracking; therefore, predetermined plans

for the part will dictate acceptance or rejection. Cracks

are normally unacceptable unless their location rests within

nonstressed areas of the part. Forging laps and cracks are

illustrated in Appendix I.

Discontinuity in the Weld

Another form of discontinuity results from any and all

of the several welding operations. Because welding causes

sections of metal to fuse togsther through meling actions,

chance provides a means for inclusions to become entrapped

in the molten pool. The inclusion is a discontinuity and is

sometimes found in the fusion zone. Usually, these small

particles of nonmetal float to the surface prior to solid-

ification, but too often, some become entrapped within the

solid metal.

Because welding involves the heating and cooling of a

metal, a temperature differential always exists along the

path of fusion. Because this temperature difference exists,

uneven stresses prevail which tend to warp and tear the metal.

Sometimes, a starlike crack will appear in the weld as the

result of over stress. When the metal is restrained to pre-

vent warping, transverse cracks may occur in the

24weld. The

20

transverse crack occurs across the weld while the lonE;itudinal

crack occurs parallel to the weld.

Another unwanted discontinuity resulting from welding

is the pin hole. This small separation in the metal results

from porosity or rising gas oubbles. Good welding techniques

and proper welding temperatures help eliminate the presence

of the pin hole and the inclusion.

Finally, faulty welding techniques often result in

improperly shaped beads. When stress follows the surface

contour of a part, an undercut in the welded metal provides

a stress raiser and a potential trouble spot. Also, lack of

fusion and poor penetration of the weld act as stress concen-

tration points when the part is loaded. Therefore, inspection

must be carefully aimed at bead shape and dimensions and these

relationships with the parent metal.

Because the welded zone of metal is cast and frequently

joins wrought metal, strength variations in the metal exist

across the welded zone. The shape of the bead across the

welded zone provides the shape of the stress path across the

zone. Undercut, poor fusion, inadequate penetration, inclu-

sions, porosity, cracks, and craters provide stress detours

and subsequent points of stress concentration.

A welded joint that is highly stressed must transmit the

stress pattern effecLively. The presence of discontinuities

in the fusion zone acts as possitle points for failure. The

nondestructive test must therefore search for these flaws and

find them. Welding flaws are illustrated in Appendix J.

21

Discontinuities are found in other types of manufactured

products, but the prInciples of their creation have been

noted in this summary. It can be safely stated that the

search for these unwanted flaws must continue with aggressive

efforts. The nondestructive test therefore, seeks out these

undesirables and arranges for their judgement.

Zt;

Objectives

The understanding of the origin and significance of

discontinuities is vital in the evallstion of parts which

have been previously tested and inspected by the nondestruc-

tive testing process. Objectives to be obtained in this

phase of instruction are listed below.

I. The trainee should:

A. Be familiar with the main processes used in the

manufacture of parts.

B. Be especially aware of the actions occurring

inside the metal during the pouring, solidification, and

forming sequences.

C. Be familiar with the types, shapes, sizes, and

locations of typical discontinuities.

D. Be cognizant of stress relations to load and the

resultant stress patterns.

II. The trainee will be able to:

A. Differentiate among the several discontinuities.

B. Relate the possible cause of the discontinuity.

C. Understand the significance of the particular

discontinuity.

D. Recapitulate the possible history of the part

and then relate this history to the discontinuity.

E. Determine the degree of severity of the discon-

tinuity.

27 22

23

F. Correlate the discontinuity with a view of

acceptance or rejection of the part.

Outline of Key Points

I. Metal refinement and production

A. .0res

1. Ferrous and nonferrous2. Mining ore3. Mechanical separation and refinementL. Furnace refinement processes

B. Ingot production

1. Reheating for further refinement2. Types, shapes, and sizes

C. Casting production

1. Types, shapes, and sizes

D. Wrought shapes

1. Principles of wrought processes2. Types of processes3. Kinds of parts

II. The Casting

A. Kinds of metals used in casting

1. Ferrous group2. Nonferrous group

B. Molds

1. Types, shapes, and sizes2. Mold materials

C. Pure metals and alloys

1. Typical elements and alloys2. Chemistry of metals3. Physical constants of metals4. Mechanical properties5. Grain structure and pattern6. Allotropic changes

2 5

D. Pouring processes

1. Liquid action as temperature drops2. Formation of solid nuclei3. Slags and flotation4. Gases, internal and external5. Liclusions, specific g:avity, and time6. Coefficients of expansions7. Nuclei growth patterns8. Gates, sprues and risers9. Escape holes for gas

10. Thick and thin section factors11. Top portions of solidified metal

E. The finished casting

1. Birth of discontinuities upon aolidification2. Tha cold shut3. The inclusion4. The pin hole and porosity5. The blow hole6. The tear or crack7. The void8. Sub-surface defects9. Surface defects

F. Heat treating processes

1. Ferrous procedures2. Nonferrous procedures

G. Appearance of new discontinuities

1. Cracks2. Causes

H. Surface irregularities

1. Mold marks2. Machine marks

:II. The ingot

A. Ferrous and nonferrous

1. Chemistry of metal2. Physics of metal

B. Molds

1. Mold materials2. Sizes, shapes, and types3. Principle of mold cooling

30

26

C. Pouring processes

1. Liquidus to solidus curves2. Slags and flotation3. Gases, internal and external4. Inclusion characteristics5. From liquid to solid6. Actions along bottom and sides of mold7. Actions at top of mold8. Pipe and porosity

D. The cold ingot

1. Grain structure2. Structural patterns3. Surface conditions4. Top section irregularities5. Birth of discontinuity

IV. Wrought sections and parts

A. Slabs and billets

1. Reduction in size of ingot2. Shapes of smaller sizes

B. The plate and sheet

1. Geometry changes to plate and sheet2. The rolling process3. Discontinuity dimensional changes4. Flat and pancake types of discontinuities5. Rounded voids to elongated laminations

C. The bar and rod

1. Geometrical shape changes2. Discontinuity elongation to stringers3. The surface seam and the internal stringer4. Curved flaws to elongated

D. The pipe

1. Curved sheet to welded pipe2. The lamination and the stringer3. 0..c.ide action and the seam

E. The tube and other extrusions

1. Piercing processes and extrusions2. Mandrel movement3. Surface parallel seams

3'1

27

4. The helical seam5. Inside and outside flaws6. Discontinuity patterns

F. The wire

1. Geometry of bar and rod to wil'e2. Discontinuity transfer to wire

G. The forging

1. The lap2. The discontinuity3. The internal burst4. The surface burst5. The crack

V. The welded part

A. The fusion zone

1. Metallurgy of the weld2. Cast metal joined to wrought or cast3. Bead shape and dimensions4. Heat and cooling effects5. Expansion and contraction factors6. Discontinuity birth on cooling

B. Geometry factors

1. The bead shape2. Penetration3. Undercut4. Inadequate fusion

C. Discontinuity types

1. Inclusions2. Cracks; heat treating, tears, and fatigue3. Voids; porosity4. Irregularities

VI. Design factors

A. Mechanical properties

1. Loads and reactions2. Stress patterns3. Material factors

32

B. Part's use

28

1. Operating conditions2. Safety factors in stress

C. Discontinuity data

VII. Discontinuities

A. Birth and evaluation

1. Environmental factors2. Geometry conditions3. Chemistry and physics factorsL. Final shape, size, and location

B. Relationship to load carrying ability

1. Stress pattern and discontinuity2. Elastic nature of stress

33

CHAPTER III

LIQUID PENETRANT METHOD

The liquid penetrant method of nendestructive testing

is based upon the entry of a penetrating liquid into a dis-

continuity. Because the special penetrant must be able to

enter the diqcontinuity, only surface types of flaws and

irregularities can be evaluated by this method. The pene-trant is usually an oil in which either' a colored dye is added

or a fluorescent powder is suspended.

If a penetrant is allowed to soak at the surface of asolid materialj some of the penetram will enter a crack orpin hole if these discontinuities are open to the surface.

When the part's surface is then washed so that all penetrantis removed, a small amount of penetrant will later appear at

the surface, if any had entered a discontinuity. If this late

appearing penetrant contains a colored dye, visual observationand inspection will indicate its origin. If t;he Penetrant is

fluorescent, inspection will also indicate its origin in the

presence of black light. Black light is in the ultravioletspeCtrum of light rays und exists in the vicinity of 3600

angstrom units. The penetrant method is used on all solid

materials, except those of a porous nature. These solid mater-

ials include the metals, plastics, and ceramics.

29

30

Testing and Inspection Techniques

Penetrants are manufactured according to different

,specifications; therefore, the operator should review the

instructions for use as indicated by the manufacturer.

Because surface discontinuities exist in many types, the

penetrant must be capable of enterincL. any type of surface

irregularity. Capillary action occurs during the process of

penetrant entry. Much of this action is associated with

adhesion and cohesion forces. Also, the penetrant's viscosity,

along with pulling forces, cause the liquid to move into sur-

face breaks and proceed to the boi-,tom of the openings.

Sometimes, air is entrapped ahead of flte penetrant causing

a slowing down of penetration. In these respects, thin cracks

often allow penetrant entry easier access than do lar'er po-

rosity holes because of the possibility of entrapped air in

the hole.

Penetrants may be placed on the surface of parts by

spraying, dipping, or swabbing. Room temperature is often

acceptable for conducting this process. Often, the porta-

ble type of arrangement allows spraying from pressurized cans.

On the other hand, heavy parts are easily processed oy im-

mersion techniques. Because excess pen:trant must be removed,

washing is accomplished by any feasible means. Spray washing

is acceptable when pressures do not exceed 40 psi. and the

spray angle does not exceed 40 degrees. Immersion washinF, is

a common process because of its speed in penetrant removal.

35

31

In order that surface inspection be effectively eval-

uated, the discontinuity must be outlined so that the

operator can see it. After removal of excess penetrant, the

ptu.t is .iried at temperatures below 212 derees W. and allowed

to set for a short period of time. This dwelling period

allows bleedin of any penetrant from a discontinuity. Bleed-

Inez is expedited with the use of a developer (powder). The

ueveloper accelerates the emerging of the retained penetrant

and helps to spread it at the discontinuity. When dyes or

fluoreseent particles are added to the very thin liquid pene-

trant, visual observation is facilitated. Colored dyes mark

their presence at all surface contour breaks and are visible

in t1.(3 'essence of white light. Often, a more effective

inspection is accomplished when fluorescent particles are

placed in the penetrant. When bleeding occurs during the

developin5 process, a black li3ht causes the emerged liquid

to fluoresce. The discontinuity is clearly outlined.

Cleaning of Part

When a part is to be tested and inspected oy the liqui71

penetrant method, thorough cleaning of the part is requirc4.

There are several processes available for cleanini; such as

detergents, steam, vapors, and solvents. Because a -)art is

often contaminated with various types of unwanted materials,

consideration must be given to the process that removes the

unwanted zrease, dirt, paint, and scale without doin injury

20

to thi. maturin]. As an exatripls, wA.re brushinp, or bAastin

a surface (especially soft mqterials) is not dosiraple because

thc, mhanical action may cal,qe LhE metal at a discontinuity

to foli over and hide the break. Pl9ted materials require

platinr, removal. Parts that have been machinel just prior

to inspection may regure burr removal with acid or al,caline

etch. Neutralization of the material's surface is then re-

quired immediately follot,rimr the etching process. In other

words, the parent material must be available to the penetrant

in order that all surface irre,Lularf_ties will be exposed.

Equipment

The liquid penetrant method of nondes[ ctive testing

lends itself favorably to local fabrication of test benches

and inspection booths. However, manufaccurers have provided

various types of equipment for completing the inspection

process. Basically, a means must be available for holdin and

processin; the parts to be tested. A table top or ben&a

arrangement usually suffices. Appendix K shows a simplified

process arranement of locally manufactured equipment used in

conjunction with manufacturers' equipment. Station A is merely

a restin,_; place to assemble the parts to be tested, only after

they have been thoroughly cleaned. Station 33 serves as a

platform for arranoing the parts in some sort of testinj se-

quence. Station C is the soakin;L. tank. Parts ars soakes. in

the liquid penetrant for a ;3iven period of time in accordance

with the manufacturer's instructions. After the soak, par1,s

33

are allowed to drain at Station D. Should there have been

any discontinuities at the surface of the part, the pene-

trant would have entered and would have been retained for

a snort p'-iriod of time. Station D allows excess penetrant

to dra4.n from the surface. In a short while, th3 part is

then wash.1 free of the penetrant at Station E. Washing may

include detergent, steam, vapor, solvent, or other processes,

depending on the type of penetrant. Station F provides an

examination station to assure tnat all penetrant has been

removed from the surface. A black l.Ight is often used at

this station to ascertain a clean surface. Station G pro-

vides fo 7. drying of the part. After a short period in tae

dryer (or at room temperature), a wet or dry developer is

applied to the part at Station H for the purpose of drawing

out any penetrant that may have entered a discontinuity. If

t7o.e rret method is used, drying will again be required. If

needed, visual inspection of the part is available at Station I.

Final inspection is then completed at Station J. Here, white

light for colored dye is used or a black light is used for

energizing the fluorescent particles. Either way, the surface

irregularities are revealed in sharp contrast to the surface.

Prior to release of the inspected parts, they are then thor-

oughly washed to remove all traces of the inspection medium.

Appendix K also indicates a discontinuity discovered by this

process.

38

Evaluation

Following the testing and inspection processes, evalua-

tion is accomplished. In effect, evaluation is the end process

of testing. The ability of the operator to adequately test

and inspect parts is focused on his ability to evaluate what

he sees. Evaluation is critical. Wrong judgement in evalua-

tion could allow subsequent part failure and possible disaster

to persodnel. Therefore, operators mubt be well informed as

to the meaning of the inspection.

Safety Precautions

A few safety precautions are necessary when handling

penetrants. Fumes from the several liquids can be injuri-

ous; therefore, adequate ventilation is required during the

testing process. Also, the flash point of the penetrant may

bF) similar to that of kerosene. Low flash point oils may

catch fire; consequently, fire precautions are necessary. Do

not use oils with flash points near room temperature and do

not allow penetrants to become overheated.

Because the light beam emerging from the purple glass

filter of the inspection lamp is black light, it is not

within the injurious spectrum of ultraviolet. Avoid, how-

ever, a direct view into the light.

3110

Objectives

Objectives of the liquid penetrant method of nondestruc-

tive testing are stated below.

I. The trainee should:

A. Understand the principles governing the liquid

penetremt testing and inspection procesL.

B. Be familiar with the various types of parts

which are commonly tested with the aid of penetrating liquid.

C. Be coGnizant of the routine procedures involved

in accomplishing the test.

D. Understand the requirements for a specific

testing technique and be able to select the proper technique.

E. Understand the advantages and disadvantages ofthe test.

F. Comprehsnd the reasons for visual indications

on the material's surface.

G. Realize the need for increased objectivity instandar0.s.

II. The trainee will be able to:

A. Use typical penetrant units cf equipment.

B. Decide on necessary inspection items needed

in completing the inspection.

C. Follow an authorized testing procedure.

D. Differentiate among the several surface irreg-ularities.

36

E. Use white and black light efficiently in the

inspection process.

F. Use the dye process effectively.

G. Identify surface discontinuities and other

surface type flaws.

H. Analyze the total inspection results.

I. Evaluate the total situation.

J. Accept or reject each indication.

41

Outline of Key Points

I. Equipment

A. .0peratorts ability to use

1. Basic principles of the test2. Purposes of the test3. Functions of equipment4. Basic understanding of operation5. Exercises in use of equipment

B. Spot check type

1. Local needs2. Group of canned testing materials3. Sequence of use4. Understanding of principles

C. Dye facilities

1. Types of dyes2. Purposes and principles of application3. White light

D. Fluorescent capability

1. Principles of penetrant application2. Reaction of penetrant in black light3. Need for black light processes

E. Wet and dry methods

1. Types of penetrants2. Emulsifiers3. Washing controlL. Developing procedures5. Types of developers6. Setting and drying principles7. Testing and inspection pz.ocesses8. White and black lighting

F. Portable type

1. Need for mobility2. Emergency inspections3. Effectiveness of procedures4. Units of complete set

38

G. Stationary type

1. Sequential functions2. Size and shape to suit needs3. Penetrant application and draining stations4. Ovens and resting stations5. Black light booth6. Autamated

II. Surface preparation

A. Degreasing processes

1. Requirements for clean surfaces2. Detergents, solvents, and vapors3. Care of original surface during cleaning4. Cleaning vs. the kind of material

B. Scale removal

1. Mechanical and hand removal2. Care of original surfaces; danger to surface3. Nature of scale euad related coatings

C. Paint and plating removal

1. Need for removal2. Paint removers and procedures3. Plating xmoval procedures

III. Penetrarts

A. Purpose of penetrants

1. Mobility and penetration capability2. Vehicle for inspection particles3. Principles of mobility and penetration

B. Preparation of penetrants

1. Need for particular type2. Kinds and percentages of mixtures3. Need for several types

C. Water washable fluorescent

1. Penetrant application2. Setting time3. Need for controlled washing

39

D. Post-emulsification fluorescent

1. Purpose of emulsifiers2. Care in procedural applications3. Requirements

E. Water emulsification visible dye

1. Requirements for dye procesvms2. Water emulsification processes3. Reaction of visible dyes4. Special uses on certain metals

F. Application to surfaces

1. Spray processes2. Dipping and soaking processes3. Portable and stationary applications4. Proper observance during application5. Need for complete coverage

G. Area temperature

1. Need for proper application temperatures2. Temperatures of penetrant, parts, and atmosphereH. Emulsifiers

1. Flow or dipping processes required2. Precautions against penetrant removal

I. Safety precautions

1. Fire hazards2. Flash and fire points of penetrants3. Fumes4. Eye and skin protection

IV. Washing

A. Coarse spray

1. Bombardment effects on surface2. Need for controlled pressures3. Volume controlL. Temperature control

B. Solid stream or dip

1. Less impact on surfaces2. Greater coverage vs. time3. Opportunity for soak

441

C. Liquid temperature

1. Variations in room temperature2. Advantage of warm liquid

D. Black light check

1. Need to have clean surfaces2. Fast inspection of surfaces3. Things to look for

V. Developer

A. Purpose of developers

1. Application procedures2. Types of developers3. Actions of developers

B. Wet procedure

1. Need for wet processes2. Similarity to penetrant processes

C. Drying time

1. Draining time2. Drying temperature and time3. Air circulation at approximately 212 degrees F.4. Need for drying time controlS. Actions of penetrant during drying

D. Dry procedure

1. Need for drying after washing2. Application of dry powder3. Surface coverage requirements

E. Persistence characteristics

Holding power of penetrant to discontinuity2. Capabilities of developers

VI. Inspection with black light

A. Procedures

1. Need for sequential processes2. Prior need for white light3. Reflection angles of black light4. Need for movement of black light

45

B. Illumination levels

1. Proper types of equipment2. Manufacturer's recommendatio3. Specification requirements

C. Black light filters

1. Need for proper filter2. The angstrom unit and wavelength3. Care of the filter

D. Black light intensities

1. The ultraviolet spectrum2. Need for prior use of white light3. The purple filter

Control blocks

1. Need for standards and references2. Control blocks of different materials3. Specification requirements4. Shapes, sizes, and uses

F. Surface crack recognition

1. Surface inspection capability only2. Crack characteristics3. Types and shapes of cracks4. Grain structure relationship to crackS. Crack development6. Crack orientation to stress patterns7. The jagged edges (possible need for magnification)

G. Porosity at surfaces

1. Causes of porosity at surface2. Recognition of the rounde:a . edge depression3. Quantity in given areas of surface4. Reiatiomhip to stress patterns

H. Shut and seam recognition

L. The smooth and rounded edge type2. The straight line seam3. The nonfused areas of metal4. Recognition characteristics

I. Machine marks

1. Recognition of Lte straight line2. Depth factors3. Edge characteristics4. Pointed and dull marks5. Similarities to other discontinuities

J. Post cleaning processes

1. Need for testing materials removal2. Processes used in cleaning3. The proper drying procedures

VII. Evaluation techniques

A. Need for standards

1. Comparison needs in accuracy2. Known defects vs. the unknown3. Specification requirements4. Understanding of barlic metallurgy5. Understanding of nonmetal manui'acture6. Understanding of basic metals manufacture7. Cognizance of discontinuity development8. Realization of stress flow vs. load9. Critical factors in surface stress

B. Appraisal of object inspected

1. Individual ability to appraise2. Application of rules for acceptance3. Causes for rejection4. The point between acceptance and rejection5. ::::ceptance of responsibility

47

CHAPTER IV

MAGNETIC PARTICLE TESTING

Magnetic particle testing is based on the principle of

magnets and magnetization of ferromagnetic materials. When

a ferromagnetic part has its molecules aligned in a single

direction by magnetization, one end of the metal becomes a

north pole while the other end becomes a south pole. Mag-

netic lines of force then flow from pole to pole by leaving

one pole and completing the circuit through the surrounding

air to the opposite pole. A flux pattern group of magnetic

lines of fo,ae then surrounds the magnet. It is on the basis

relating to various aspec:ts of the bar and circulsr shaped mag-

nets that this method of nondestructive testing is conducted.

All metals cannot be magnetized; therefore, the magnetic

particle test is reserved for those that are ferromagnetic.

Most of the cast irons and steels however, which are used in

manufacturing processes are subject to becoming magnetized

Jhen brought within the influence of magnetic flux fields.

These metals have a high permeability factor. In this respect,

the flux field develops a pattern about the magnet whereby

surface and neer surface tests can be made to etermine the

mechanical soundness of the surfaca metal. The technician

then is concerned anout the continuity of the metal; that is,

an indication if solid metal exists which aontains no flaws.

43 it Sit

44

Principles of Testing

When a current flows through a conductor, magnetic lines

of force are established at right angles to the current flow.

According to the right hand rule in electricity, when a cur-

rent carrying conductor is held in the right hand, the fingers

point in the direction of flux flow when the thumb points in

the direction of current; flow. This rule govt-, the patterns

of flux fields (concentrated magnetic lines of lorce) with

respect to the geometrical shape of the conductor, whether

the current flows through the part in a straight line op around

it by means of a coil. Flux flow in the wire of a coil is

90 degrees to the flow of curmnt and this results in a group-

ing of flux lines flowing longitudinally through the coil.

When a bar magnPt is broken, several magnets are formed,

each having a north and south pole. On the other 'And, if a

ba:, magnet is slightly cut at right angles to its axis, a

north and south pole will be estahliahadat the cut in addi-;

tion to the existing poles at each end. In other words, the

break A.n the surface contour causd a flux field distortion

around the bottom and sides of the break so that a flux leak

existed. This leak produced the north-south pole arrangement

because the flux field cut the break at 90 degrees. A lO31-

tudinal flux field was established when the flux flowed

longitud.l.rIlly through the part.

When a bar magnet is cut alont, it,F; flux field

Clows parallel to the cut and has little opportunity in

41)

establishing a strong north-south pole relationship due to

flux lines contacting the ends of the cut instead of the

sides. Should the flux field be changed by 90 degrees, a

strong north-south pole situation would then exist at the

break.

carcular Field

Magnets are produced by surges of electrical current

being either passed throucth the permeable metal or being

passed around the metal. When the current flows through the

part from end to end, a flux field is established at 90 degrees

to the flow of current. The flux field is circular and cir-

culates within and beyond the surface of the magnetized part.

This circular teamique is used in many ways in the search

for discontinuities and other flaws within the metal. The

circular flux field utilizes the head shot process. As long

as the current flows, the flux field exists, but when the

current ceases to flow, the flux field collapses so that mostof the magnetic of force disappear and no magnetism

remains. Appendix L illustrates some of these testing prin-

ciples.

When two prods are used to allow current to flow through

designated regions of a part, the flux field is establishedaround each prodls contact point and within the metal. This

circular flux pattern extends to the limits of energy which

is governed by the amount of current flow.

Another circular flux field is established when a

straight conductor carries a current'within, but not in con-

tact with, a hollow part. Current flow through the conductor

causes flux lines to bo established at 90 degrees to the cur-

rent flow. Because the hollow part, a pipe or tube for example,

exists within the flux pattern, a circular flux field is es-

tablished within and also surrounding the part.

Longitudinal Field

Another technique is to allow the current to flow through

a coil. Because the wire of the coil is no longer straight,

but shaped into a helix, the flux field circulates from end

to end so that the central portlon of ;.he coil is energized

with magnetic lines of force. When a ferromagnetic part is

inserted within the coil, a longitudinal flux field is es-

tablished along the axis of the part. Again, the flux field

is 90 degrees to the directional flow of current. A modified

technique can be used by fabricating a "U" shaped magnet.

When the part is placed between the poles, longitudinal flux

lines also move along the axis of th. part. Appendix L

illustratec some of these principles.

Polar Environments

The magnetic particle testing process then utIlizes

circular and longitudinal techniques to cause changes in

direction of flux flow on or nea._ the surface of a metal.

,nenever a discontinuity '4: metal (crack or inclusion) exists

14-7

in the presence of a flux field, flux leakage will occur and

a polar environment will be established. Should the discon-

tinuity exist at approximately 45 degrees from the flux

pattern, a weaker indication will be seen. Sometimes, a

swinging magnetic field can be utilized to a t discontin-

uities which resl. near the border line zones of circular and

longitudinal testing capabilities.

Hard steels will retain magnetism while soft steels will

lose it when the current ceases. Because permanent magnets

are usually made from hardened steel, a continuous flux pattern

surrounds the magnet. When magnetism is established in sof4-,

steels, the ma,netism disappears when the flux field ceases.

On the other hand, some metals have the residual ability to

hold a molecular alignment while ,chers have little retention

capability. Because of this difference in some metals to re-

tain magnetism, the magnetization proce:Is sometimes requires

continuous flow of current to retain the flux field. This

continuous process applies particularly to soft metal. When

harder metals are magnetized, a momentary surge of current

often leaves a residual flux field. The use of hard metals

eliminates the need for a continuous flow of carrent.

Current Use

Magnetization of metals is accomplished by both direct

and altarnating current. When direc, current or pulsating

direct current is used, a molecular alignment in the part to

4-8

be tested quickly establishes a north-south pole arrangement.

Any discontinuities on or near the surface of the part will

immediately provide north and south poles because of the

detouring and leaking flux field. When alternating current

is used, the break in part contour at the surface will immedi-

ately establish alternating north and south poles at the break.

The polar change will be synchron3 with the frequency of

the cu2r3nt. Geometry of the part, its condition, and location

of flaws determine the type of current to use. Alternating

current flows closer to the surface whereas direct current

flows aeeper. Neither current will suffice for testing deep

regions within a metal. Defects on or near the part's surface

however can be detected by the magnetic particle method.

Inspect!on Techniques

Even though north and south poles are establidhed on a

metalls surface because of discontinufties or surface irreg-

ularities, they cannot be detected without the aasistance of

a ferromagnetic powder. Because a magnet attracts an iron

containing powder, a specially prepared iron powder is then

spread across the entire surface of the part being tested,

while the part is under the influence of a flux field. When

the nri,n-south /..)3e situation occurs, the powder arranges

itself at the flux leakage and tends to outline the shape of

the flaw. The powder may be applied onto the part either dry

or wet. The wet methcd uses a thin oil aimilar to kerosene as

4-9

the vehicle for carrying the powder in suspension to the area

of flux leakage. Obviously, operators must be positive that

the testing medium covers the part in all areas and that both

the circular ana 1')ngitudinal techniques are used to assure

the dete;Lion of unsatisfactory s'Auations in any position

within the metal.

Application of the testing medium to the surface of the

magnetized part allows an experienced operator to inspect all

surface areas for clues and indications of unsound metal.

Magnetization by direct current will prcvide a pattern of

closely held powder particles at the flux leakage or along

the detouring flux path. AltbAanating current causes the par-

ticles to vibrate at the flaw due to the constant polar

change, Should a fluorescent Aaterial be added to t'3 test-

ing pawder, an increase in inspection capability is often

produced when a black light ls focused on the part's surface.

The black light provides a greater color contra because of

fluorescence while the flux leakage holds the powderymaterial

in an outliae form.

Equipment

Equipment for conducting the magnetic particle testing

process is produced by several manufacturers. SOMB equipment

is portable in order that field tests can be made, a welded

pipeline for example. Other equipment is stationary arad.04,-CF

fairly fixed becalise of its bulk and weight. Also, this

54

50

fixed process lends itself to automation and rapid production

of inspected parts. Basically, a bench type arrangement is

needed for holding the parts, for manipulation of the elec-

trical contact mechanisms, and for holding the tanks containing

the inspection liquid. This type of arrangement allows for

ease of inspection. While the part is held between the elec-

rical contact jawth of the mchine and while the flux field

exists, the inspection liquid is pumped onto the surfaces of

the part. Any discontinuities at or near right angles to the

flux fiJld will be outlined by the magnetic powder within the

liquid. Following this circular testing technique, the part

is then placed within the flux field of the coil and subjected

to loligitudinal inspection. Aldpendix L represents a fixed

testing and inspection installation and provides an illustra-

tion of the testing technique. According to this arrangement,

both circular and longitudinal techniques can then be accom-

plished. In order that numerous other testing techniques

can be performed, attachments and accessories are necessary.

Evaluation

Again, evaluation of the sight picture is necessary in

order to determine serviceability of the part. A familiar

knowledge of metallurgy is esseAtial in order to fcrm a

decision. Should wrong judgement be made, serious conse-

quences may result. As an example, if a small fatigue crack

is evaluated as a tool mark, part failure and disaster will

55

ultimately follow. Should human life be dependent on proper

stress reaction in a metal, the metal must favorably react

to the load when called upon or life may be endangered.

Unsatisfactory discontinuities and irregularities found in

the metal are cause for rejection.

Demagnetization

Following the inspection process, all parts are deinag-

n,tized by subjecting them to the vibrating and weakening

flux fields of alternating current. Following demagnetiza-

tion, parts are cleaned.

Saf4ley Precautions

The main safety precau i.ons related to this testing

process are associated with the fundamentals of electricity.

Care must he exercised to prevent s.Lectrical shock and burn.

In some instances, fumes from the inspection liquid are un-

healthy. In addition, the liquid can often be a fire hazard.

Objectives

Objectives of the magnetic particle method of nondes-

tructive testing are stated below.

I. The trainee should:

A. Understand the principles governing the magnetic

particle testing and inspection process.

B. Be familiar with the various types of parts

which are commonly tested by use of magnetic lines of force.

C. Be cognizpnt of the routine procedures involved

in accomplishing the

D. Understand the requirements for a specific

technique and be able to select the proper technique.

E. Understand the advantages and disadvantages of

a specific test.

F. Comprehend the reason for surface and sub-surface

indications.

II. The trainee will be able to:

A. Use typical equipment pertinent to magnetic

particle testing.

B. Use the needed equipment attachments and

accessories related to specific techniques.

C. Follow an authorized testing procedure.

D. Use circular and longitudinal techniques in

searching for discontinuities.

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53

E. Differentiate among the several discontinuity

patterns at the surface.

F. Evaluate a sub-surface indication.

G. Analyze specific and total inspection results.

H. Evaluate the total inspection situation.

I. Accept or reject the individual indications.

58

Outline of Key Points

I. Equipment

A. Operator's ability to use

1. Understanding of test principles2. Knowledge of test purposes3. Types of equipment and functions4. Attachments and accessoriesS. Exercises in use of equipment

B. Portable type

1. Reason for portable equipment2. Capabilities of portable types3. Similarity to stationary equipment4. Need for increased capabilities

C. Stationary type

1. Capability to handle large and heavy parts2. Flexibility in use3. Need for stationary types4. Automation needs5. Use of accessories and attachments

D. Automatic type

1. Requirements for automation2. The flow process3. Sequential operations4. Setting of tolerancesS. Control and opr:ration factors6. Alarm and rejiction mechanisms

E. Liquids and powders

1. Liquid requirements as a vehicle2. Viscosity and flash points3. Safety precautions4. Temperature needsS. Flow mechanisms6. Powder and paste contents7. Mixing procedures8. Need for accurate proportions9. Actions of the powders and dyes

55

F. Black light type

1. Black light and fluorescence2. Fluorescent material in the liquid3. Visible and black light comparisons4. Requirements in the testing cycle5. TechAiques in use

G. 'Light sensitive instruments

1. Need for instrumentation2. Light characteristics

II. Principles and purposes

A. Theory of magnetism

1. Ferromagnetic materials2. Crystalline nature of metals3. Permeability factors in metal4. Alpha and gamma ironS. Molecular alignments6. North-south polar effects7. Flux patterns8. Induced electricity9. Alternating and direct currents10. Frequency and voltage factors

11. Current calculations and needs

B. Purpose of magnetic fields

1. The magnetic line of force2. Bending of force fields3. Direction of travel of the field4. Flux line concentrations5. Polar requirements6. Surface flux strength7. Sub-surface effects

C. Ferromagnetic materials

1. The permeability factor and influence2. Body-centered cubic iron3. Wrought irons4. Steels - magnetic vs. the nonmagnetic5. Cast irons6. Temparature of part limits for testing

D. Magnets and magnetism

1. The basis for magnetism2. North and south poles

60

56

3. Current flow and flux fields4. Distance factors vs. strength of flux5. Attraction properties of opposite poles6. Internal and external flux patterns7. Phenomenon action at the discontinuity8. Permanent and temporary magnets9. Heat effects on magnetism

10. Material hardness vs. magnetic retention

E. Dry method

1. Need for dry method processes2. ProcedureL;3. Types of dry powders4. Surface irregularities, flux, and powder

F. Wet.method

1. Need for wet procedures in testing2. Procedures3. Liquid vehicle and the paste or powder4. Application processesS. Liquid flow with the powder6. Liquid contact in presence of flux

G. Filtered particle

1. Relationship to conventional tests2. Need for test

III. Flux fields

A. Rules of field

1. Right hand rule2. Current flow and flow )attern3. Density of field4. Distance factors

B. Direct aarrent

1. The steady flux field2. Directional patterns3. Depth or penetration factors4. Polar effects5. Source of current

C. Direct pulsating current

1. Similarity to direct2. Source of current production

61

57

3. The pulsatir,3 factor4. Advantages5. Typical fields

D. Alternating current

1. Polar effects2. Cyclic effects3. Surface strength characteristics4. SE.fety precautions5. Voltage and current factors6. Source of current

E. Bar magnet principles

1. Induced flux patterns2. Internal current flow3. External current flow4. Straight and curved magnets5. Flux strength6. D.C. - A.C. influences on poles7. Distance and strength factors8. Residual magnetism9. Discontinuity effects

F. Ring magnet principles

1. The internal flux pattern2. Surface discontinuity effects3. Field strengths4. The induced field

G. Continuous field

1. Life of continuous field2. Source of field3. Need for continuous field4. Characteristics of fieldS. Strength patterns

H. Residual field

1. Retention characteristics2. Retention problems3. Disadvantages and advantages4. Need for residual field5. Strength of field6. Proce.dures involved with field

I. Swinging field

1. The changing flux pattern2. Need for swinging field

58

3. Polar effects4. Comparison with stationary field

J. Length-diameter ratios

1. Dimensional understanding2. Current characteristics3. Efficiency

K. Meters and strength of field

1. Flux measurements2. Current and voltage factors3. Frequency effects4. Need for instruments

IV. Surface discontinuities

A. Cleaning processes

1. Need for surface cleaning2. Types of cleaners3. Cleaning procedures4. Safety precautions5. Fire hazards6. Fumes

B. North-south pole factors

1. Need for opposite poles2. Characteristics of pole flux3. Flux patterns and strengths4. Directional factorsS. Surface and sub-surface factors

C. Crack types

1. Metallurgical basis2. Casting effects3. Heat treating effects4. Fabrication process effects5. Grinding and welding effects6. Fatigue effects7. The jagged pattern8. Relationship of part history to crack

D. Laps, seams, and pits

1. The surface characteristics2. Straight line factors of the seam3. Forging and rolling irregularities

63

59

L. The casting or welding irregularities5. Discontinuity patterns

E. Machine marks

1. Contrast to the discontinuity2. Depth vs. discontinuity similarity3. Types of marks - from sl!.ding and whirling tools.4. Recognition factors

F. Geometric effects

1. Geometry of the part2. Mass of material under flux influence3. Depth characteristics of flux4. Depth of discontinuity recognition5. Solid and hollow objects6. Square and cubical shapes7. Rounded and rectangular shapes8. Wire9. Nonsymmetrical ohapes

Surface defects

A. Surface indications

1. Particle concentrations2. Patterns of particle concentration3. Directional properties of indications4. Strong vs. weak patterns5. Part's geometry effects6. Discontinuity orientation to flux fiela7. Sub-surface indications

B. Holes and porosity

I. Round ended indications2. Circular patterns with strong centers

C. Metallic discontinuities

1. Metallic separations2. Voids - holes and cracks3. Inclusions - chemistry4. Orientation to flux field5. Shape :I' discontinuity

D. Depth from surface relationships

1. Field strength decrease in depth2. Pattern strengths at surface3. Indications not open to surface4. Strength and distance relationship

64

VI. Circular techniques

A. Procedures

60

1. Principles of flux flow2. Current calculations3. Depth factor considerationsL. Proper contactS. Precautions - safety6. Precautions - overheating

B. Right hand rule and flaws

1. Current flow and flux pattern2. Application of powder or liquid3. Intensity of flux patterns4. Direct and indirect current indications5. Continuous flux6. Residual flux7. Part orientation vs. flux patterns8. Discont4.nuity indications9. Flaw identification

C. Bud-to-end current conduction

1. Part geometry considerations2. Suitability of contact points3. Types of discontinuities detected4. Significance of weak indications5. Current factors6. Need for accessories and attachments

D. Contact plates

1. Contact surfaces required2. Adequacy of current conduction3. Special shapes and needs

E. Contact prods and yokes

1. Requirements for prods and yokes2. Current carrying capabilities3. Cables and attachmentsi. Shapes and sizes

F. Current calculations

1. Formulas2. Current needs3. Types of current needed

65

61

G. Overheating precautions

1. Charr_cteristics of different currents2. Size of part vs. current need3. Current saturation4. Consequences of metal heating

H. Types of irregularitie5

1. The internal discontinuity2. The surface discontinuity3. Theory of discontinuity development4. Rounded or jagged shaped5. Long and continuous types

VII. Longitudinal technique

A. Procedures

1. Patterns of flux fields2. Strength of fields3. Induced fieldsL. Types of discontinuities detected5. Extarnal current flow6. Shapes and sizes of coils7. Application of liquid or powder in influence

of flux field

B. External flow of current

1. Principles of induced flux fields2. Geometry of part to be inspected3. Theory of discontinuity interception

C. Use of coils and cables

1. Current directional flow vs. flux field2. Strength of field3. Ampere turns of cable4. Shapes, sizes, and current capacities

D. Current calculations

1. Formulas2. Types of current required3. Current demand

E. Types of irregularities

1. Discontinuities across the axis2. Voids and inclusions

62

3. Shapes, patterns, and orientation4. F?.ux flow and bending

F. Demagnetization procedures

1. Need for demagnetization of parts2, Current frequency attack on molecular

orientation3. Heat factors and precautions4. Need for collapsing flux fields5. Cleaning of parts

VIII. Evaluation techniques

A. Use of standards

1. Need for standards and references2. Measurement of known with unknown3. Specifications and certifieations4. EMPloyment of locally made standards5. Comparison techniques

B. Defect appraisal

1. History of part2. Manufacturing process3. Possible causes for defect4. Use of part5. Stress reaction capabilities6. Acceptance and rejection criteria7. Use of tolerances

67

CHAPTER V

EDDY CURRENT TESTING

Eddy current testing is a recent type of nondestructive

test in which an alternating electric current is used to in-

duce a secondary current into a conductor. This induced

current is provided by a coil of wire. Because the alter-

nating current reverses its directional flow in the coil

with the frequenny, the electromagnetic flux patterns and

induced currents in the conductor also reverse. In effect,

a moving path of inuuced electrical currents exists within

the conductor as long as the influence of the primary effects

of the ' xist. When the conductor becomes the part

to be ttv-, a testing situation ib t:stablished. Eddy cur-

rent density is proportional to the coil's magnetic field.

As in other nondestructive testing processes, the test

seeks the presence of some type of discontinuity la a mater-

ial. Although eddy current may be used to determine material

thickness and to find some mechanical propertie, the primary

purpose of its use for material soundness is the detection of

discontinuities. Eddy current testing equipment, more than

any other type of nondestructive testing equipment, must be

especially fabricated to suit the particular test situation.

Because many variables exist in eddy current testing which

influence the outcome of the test, special consideration must

614_

be given to the control and or isolation of these variables.Therefore, the test is reserved for a more restricted typeof investigation.

Principles of the Test

When a test coil is energized with an alternating current,flux patterns form about the coil. If the coil Is moved inclose proximity to a material which provides a flow of elec-tricity, a movement of free electrons in the material willimmediately establish a circulating type of organized path.The direction of this path of oscillating electrons is deter-mined by the shape and type of test coil; however, the currentflow is parallel to the surface. When the atomic lattice ofthe material being tested is orderly, no scattering of elec-trons occurs from the influence of eddy current, but when anunorganized lattice exists (a discontinuity), scattering ofcertain electrons occurs. In turn, this scattering or op, -

sition from the test part to the test coil's magnetic fieldoccurs and is detectable with proper instrumentation.

The depth of penetration of eddy current flow is governedby the conductivity of the material being tested and thefrequency-of the test coil. The depth of penetration or dis-tribution of eddy current flow increases as frequency islowered, within limits, and decreases as frequency is increased.This is a general rule because other factors help to influencethe net result of distribution such as the closeness of coil

69

65

to the part (coupling) and magnetic (permeability) properties

of the material. Magnetic materials cause a decrease in pen-

etration.

The heart of the eddy current test system is the test

coil. The wire in the coil has a resistance to a flow of

electric current and when the wire is formed into a coil, an

additional factor is introdused within and around the coil.

This total electromagnetic factor or impedance provides the

basis for a common testing technique.

From the coil, induction of eddy current in the part

results. Because the part to be tested may exist in any

shape, condition, and size, test coils also require fabrica-

tion in a shape and size commensurate with the part's geom-

etry. Basically, the test coil is an extension of the

electronic system for purposes of investigating specific vol-

umes of material. Because eddy currents in the part being

tested cause flux lines which oppose the c."- _ lines,

an effective electromagnetic value results ill the test coil.

Testing Techniques

For discontinuity detection when using eddy currents,

the searching coil must be closely associated with the part

to be tested; that is, the test coil is either inside the

part, around the part, or on the part's surface. Appendix M

illustrates SOMB of these principles. As coupling of the

part to the coil increases, strength of eddy current increases;

therefore, coils are manufactured to suit the specific

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66

geometry of the part. Eddy currents flow in the direction ofthe coil's windings. If the coil is placed in a hole or a

cylinder, eddy currents circulate around the inside surfaceof the part. If the coil surrounds the part, eddy currentsflow around the perimeter of the part. If the coil is placedagainst the part, eddy currents flow at and near the surfaceunder the constant influence of the coil. Another t,echniqueis accomplished with the use of a gap probe coil. In thisprocedure, a north-south pole relationship exists on the faceof the coil. Eddy currents are then induced when the part isplaced within the flux field of the coil.

Types of Te;ts

The common types of eddy current tests are impedance,modulation, and phase analysis. frpedance testing uses astatic situation for the test while the other types of test-ing become involved with complexities. such as moving partsor interpretation of phase changes as dis-'ayed on the os-cilloscope. In the impedance test, voltage, amperage, andimpedance provide the basic situation within the coil forthe test when the coil's frequency induces eddy currents inthe material. Impedance testing is based on total changeoccurring in the impedance of a test coil. Appendix M showsa schematic arrangement of an impedance coil and its relation-ship to the voltage and current factors.

Specific procedures for conducting an eddy current testdepend on the technique to be used and a means for controlling

7 1

67

variableu. As an example, magnetic material requires satura-

tion with direct current to prevent flux change, as a result

of the direct current, in the part while testing is being

conducted. In this situation, the impedance coil is fre-

quently placed between direct current coils. Another factor

to be considered is the shallow depth of eddy current pene-

tration. Penetrations in excess of three-eights inch are not

common; consequently,_thick materials are reserved for other

types of testing. Also, because eddy currents flow at or near

the surface, center portions of a part are not influenced dur-

ing the test. As depth of penetration increases, eddy currents

become weaker and are less effective in carrying out their

function. Further, density of eddy current increases as coup-

ling distance is decreased. Eddy current test equipment is

shown in Appendix N.

Need for References

In order to perform an eddy current test, some means

should be available for establishing a standard or reference.

Reference blocks wi1,h known defects can be used. If the eddy

current equipment is adjusted to the reaction of a defective

specimen, the test coil will then have a reference for com-

parison. Or, if the test coil is adjusted to a homogeneous

material, the test coil will also have thia sound material as

a reference when a discontinuity is detected. The reference

may be part of the material being tested or it may be separate

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68

Reference blocks assist in locating flaws, irregularities,

and discontinuities.

Eddy Current Characteristics

Eddy currents have properties of a compressible fluid

in that they bend and compress about a discontinuity. When a

discontinuit.y, disturbs the path of a circulating eddy current,

the path Aill divide, detour around the flaw, and then join

together again in a pattern. The discontinuity therefore

impedes the eddy current flow. Density of current fluxuations

are then detected and relayed to an indicator. Much of the

impedance testing equipment includes meters and scales for

flaw indication. Howeve the oscilloscope is used frequent-

ly in other testing techniques such as in phase analysis.

The part to be tested has an influence on phase changes as

well as on impedance in the test coil as shown by the differ-

ence in current and voltage factors. Phase differences are

displayed on the oscilloscope's screen. Basically, 01, -on-

ductivity variable is separated from the almensional and

permeability variables when Using this technique. Three com-

Mon techniques in this area include linear time-base, ellipse,

and vactor point.

In modIdation analysis testing, more variables can be

separated than by impedance and phase analysis techniques.

The presence of a disaontinuity in the test coil's field

modulates the field. Because the test part is moving through

7n

69

the field, static testing is not performed. The discontin-

uity's frequency of modulation depends on transit time through

the magnetic field of the coil. Indication of changes ape

then relayed to some type of indicating or marking device.

Eddy Current in Automation

Eddy current testing techniques support automation in

many excellent ways. Fast moving steel sheets, for example,

can be constantly monitored for tb zAcness. Deviations in

tolerances immediatel7 provide marked areas on the metal

sheet where measurement deviation occurred. Also, automatic

alarms are sounded when unsatisfactory situations occur with-

in the material being tested and inspected.

Safety Precautions

Because eddy current testing involves the use of elec-

tricit7, safety precautions to 'eve} 17: r are

recommended.

Objectives

Objectives of the eddy current method of nondestructive

testing are stated below.

I. The trainee should:

A. Understand the principles governing the eddy

current testing and inspection process.

B. Be familiar with the various types of parts

which are commonly tested with eddy current.

C. Be aware of the routine procedures involved in

accomplishing the test.

D. Understand the requirements for a specifio

nique and be able to select the proper technique.

E. Understand the advantages, limitations, and

disadvantages of the test.

F. Understand the forces causing meter indications.

II. The trainee will be able to:

A. Use typical equipment pertinent to eddy current

procedures.

B. Uae needed attachments and accessories perceliar

to a specific technique.

C. Follow an authorized testing procedure.

D. Use the several types of eddy current testing

techniques in accordance with the situation.

E. Differentiate among the several discontinuity

7075

71

patterns, realizing the limited depth characteristics of

the test.

F. Analyze the total inspection situation.

G. Evaluate the total inspection situation.

H. Accept or reject the individual indications.

76

Outline of Key Points

I. Equipment

A. 'Operator's ability to use

1. Understanding of test principles2. Knowledge of material to be tested3. Familiarization with types of equipment4 Functions of equipment5. Experience in use of equipment6. Safety precautions7. Understanding of basic electronics

B. Purpose of various types

1. Types of eddy current tests2. Principles of tests3. Equipment to match the test4. Permeability and non-permeability factors

C. Automatic equipment

1. Purpose of automation2. Speed of tests3. Alarms and rejef;tion mechanisms4. Simplicity and sophistication of automation5. Rapid production possibilities

D. Design characteristics

1. Ease of design to fit need2. Flexibility of coil adaptation3. Testing capabilities and potentials

E. Indicators and meters

1. Direct and indirect indications of discontinuities2. Oscilloscope and CRT3. Scales and direct reading instruments

II. Test coil arrangements

A. Feed through

1. Geometry of part vs. geometry of coil2. Shapes and sizes of coils

72

7

73

3. Purpose of feeding throughL. Speed capabilities for testing

B. Inside test

1. Geometry of part vs. geometry of coil2. Design of coils3. Purpose of inside test4. Principles of inside test5. Comparison with feed through

C. Probe

1. Need for probes2. Length-diameter part factors3. Probe,capabilities

D. Forked

1. Need for forks2. Part geometry

E. Other shapes and sizes

1. Need for increased capabilities2. Design potentials3. Increased automation potentials

III. Impedance Plane Response

A. Feed hack

1. Inductance and resictance ratios2. Self-excited circuits3. Energy lossesk. Oscillator circuit and voltage5. Energy loss effects

B. Reactance

1. Permeability variations2. Frequency ratios3. Specimen diameter variations4. Frequency response limitations5. Oppositions to current flow6. Reactive components

C. Magnitude

1. Test and limit frequencies2. Discontinuity variations

18

74

3. Surface cracks effects4. Oscillation frequency influences

D. Vector analyses

1. Voltage variations due to specimen in coil2. Horizonta) and vertical deflection voltages3. rhase angle4. CharacteristIcs of resultant patternS. Specimen discontinuity influences6. Amplitude and phase values

E. Effects suppression

1. Influence of diameter variations2. Optimum frequencies3. Differences in ferrous and nonferrous materials4. Effective permeability

F. Cathode ray

1. Vertical and horizontal factors2. Specimen waveform3. Slit values4. Straight line and ripple effects5. Screen displays

G. Linear time base

1. Fundamental frequencies2. Mixed frequency effects3. Amplitude4. Phase shifts5. Absolute values and the test coil6. Wave signals7. Linear sweep8. Dimensional variations

IV. Eddy current principles

A. PrinCiples of eddy current

1. Induced circulating electrical current2. Surface parallel travel3. Density decreases in penetration4. Variables problems5. Coil relationships6. Frequency offects

79

B. Alternating current field

1. Build up and collapse of flux fields2. Frequency spread3. Coil shape effects4. Frequency and depth density factors5. Coil reactions

C. Empty coil voltage

1. Magnetic lines of force2. Flux density3. Current magnitude4. Basic voltage5. Insertion effects on voltage

D. Object influence in coil

1. Coils magnetizing force2. Magnetic and nonmagnetic materials3. Part's electrical conductivity4. Primary-secondary coil relationships

E. Primary coil characteristics

1. Basis for flux field2. Coil shape, size, and current flow3. Coil purpose4. Eddy current flow5. Permeability factors

F. Secondary coil characteristics

1. Relationship to primary coil2. The induced flux pattern3. Residual effects in ferrous and nonferrous

metals4. Rules of current and flux flow5. The coupling factor and its importance6. The outside and inside coil relationships7. Relationships to reference and standards8. Variable effects9. Meter readings

G. Coupling factors

1. Purpose of the couple2. Distance and strength factors3. Geometry of part and coil4. Flux direction5. Relationship to type of coil6. Permeability factor

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76

H. Signal-noise ratio

1. Impedance and voltage plane2. Control of voltages3. Signal direction4. Conductivity and discontinuity effects

I. Choice of coil

1. Part geometry2. Coupling distames3. Use of coil4. Frequency and inspection speedS. Design criteria

J. Circular direction characteristics

1. Inside and outside coil purposes2. Probes and forks3. Part geometry and frequency penetration4. Eddy current density5. Diameter of flux and current patterns6. Strength needs7. Materials conductivity8. Discontinuity effects9. Variable control

K. Surface to center factors

1. Characteristics of alternating current2. Frequency effects in depth3. Surface maximums to center minimums4. Orientation of discontinuity relationships5. Standards and calibration6. References

L. Constants

1. Analysis of variables2. Artificial and natural factors3. Known factors as basis4. Comparison techniques5. The complete coil environment

M. Amplitude and phase angle

1. Waveform and adjustment2. Vectors3. Hysteresis4. Phase changesS. CRT screen displays6. Voltage factors

SI

N. Depth penetration

77

1. Material resistance to eddy current2. Conductivity constants3. Geometry and the flux patternL. Need to know depth of penetration5. Sub-surface effects are weak6. High frequencies and shallow penetration7. Shallow penetration8. Technique partially controlled by depth factor

0. Temperature compensation

1. Frequency requirements and ratios2. Temperature coefficients of expansion3. Variations in part diameterL. Heating effects and inductance

V. Impedance

A. Impedance changes

1. Chemistry of part and impedance effects2. Coil oppositions to current flow3. Straight wire and coiled wire comparisons4. Current flowS. Voltage, current, and impedance relationships6. Part's constants influence coil impedance

B. Circuit arrangements

1. Comparison techniques2. Standard and reference areas3. Coupling relationships4. Magnetic fields of the coils5. Frequency vs. impedance6. Lift off and fill effects

C. Variation of obtlet arrangement

1. Field relationship to part2. Impedance effects3. Secondary coil arrangements4. Coil output and part variables

D. Properties of test object

1. Reference and part compared2. Primary-secondary coil arrangement3. Field intensities4. Coupling significance5. Discontinuity detection techniques

82

E. Coil - object characteristics

1. Voltage influence from reference2. Voltage influence from part3. Equal reference and part properties produce

no v.sitage4. Discontinuity in part changes voltage5. Impedance changes

VI. Permeability

A. Fundamentals

1. Magnetic lines of force2. The flux field3. Ratio of coil force to part flux densityL. Flux strength variable effectsS. Molecular relationship to domain6. Ferrous (magnetic) and nonmagnetic metals7. Alignment factors in magnetic domain8. Saturation magnetic points by direct current9. Residual magnetism

10. Coercive forces in opposite directions of field11. Hysteresis12. Ferromagnetic metals and permeability

B. Ferromagnetic objects

1. The alpha molecular arrangement2. Molecular magnetic alignment3. Iron base and ease of magnetism4. Irons, steels, and cast ironsS. Hardness of part factors6. Residual magnetism

C. Nonferromagnetic objects

1. Relative differences with ferromagnetic2. Hysteresis facts in nonmagnetic materials3. Lack of quantity of residual magnetism4. Mechanical properties influence permeability

D. Selection of frequency

1. Relationship to velocity, permeability, andconductivity

2. Electromagnetic waves3. Wave speeds and discontinuity data

VII. Field strength

A. Strength factors

83

(0

79a,

1. Coupling distance2. Frequency and depth effects1. Coil types, shapes, and current flow4. Part composition and conductivit-

B. Distribution and penetration

1. Internal and external coils2. Primary and secondary coils3. Eddy current and inductance4. Permeability5. Frequency and conductivity6. Discontinuity orientation7. Skin effect of alternating current

C. Internal and external coils

1. Part's geometry2. Encircling coils;3. Inside coil; part4. Probes for holes,5. Relationship with

VIII. Test indications

A. Conductivity

part insideoutsidepipe, and tubereferences

1. Material's molecular condition2. Electron flow capability3. The International Annealed Copper StandardsL. IACS standards and comparison techniques5. Constants vs. chemistry6. Calibration factors

B. Comparator

1. Relationships of part to standard2. Chemical and mechanical properties3. Calibration requirements4. Specifications

C. Hysteresis

1. The hysteresis loop2. The horizontal and vertical axes3. Reversing magnetic fields4. Residual magnetiam and saturation5. Material magnetic characteristics6. Loop shapes and sizes7. Sight pictures on the CRT

84

50

IX. Test object and circuitry

A. Geometry of shape

1. Cast parts and chemistry2. Wr-)ught parts; chemistry and mechanical

properties3. Hollow and solid parts4. Symnetrical and nonsymmetrical parts5. Ferrous and nonferrous parts6. Dimensional ratios

B. Cylinder test

1. Part's shape, material, and dimensions2. Test frequencies required3. Permeability factors4. Fill factors and the coil5. Conductivity6. Field strengths and distribution7. Coil requirements8. Testing techniques9. Discontinuity detection

10. Instrumentation

C. Tube tests

1. Dimensions and compositions2. Wall thickness and length3. Conductivity and permeability4. Solid and hollow parts relationships5. Voltage factors6. Frequency scales7. Discontinuity locations; inside and outside

D. Sphere test

1. Part geometry and end effects2. Conductivity and permeability effects3. Symmetrical factors of geometryL. Limit frequencies5. Voltages6. Secondary coil reactions7. Discontinuity detection

E. Sheet test

1. Primary and secondary coil arrangements2. Arrangements for fast production3. Forked coils4. Basic constants and variables

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81

5. Sheet insertion into coil effects6. Discontinuity detection

X. Irregularity recognition

A. Flaw detection and identification

1. Application of principles of the test2. Coil relationship to part3. Flaw orientation in part4. Part geometry and dimensions5. Compression and bending abilities of

eddy currents6. Coil reactions7. Instrumentation

B. Mechanical properties of object

1. Eddy current capabilities2. Types of mechanical properties3. Calibration and standards4. Principles of constants and variables5. Identification techniques

XI. Evaluation techniques

A. Use of standards

1. Requirements for reference and standards2. Specifications3. National standards and local standards4. Types, shapes, and sizes5. Comparison techniques6. Acceptable and unacceptable parts7. Acceptance and rejection criteria

B. Appraisal of object

1. History of object2. Use of object or part3. Loading factors4. Stress reaction capabilities5. Safety factors in design6. Type of discontinuity and size or shape7. Acceptance or rejection

86

CHAPTER VI

ULTRASONIC TESTING

One of the most sophisticated methods used in nondestruc-

tive testing is the ultrasonic test. Because sound waves of

exceptionally high frequencies are beamed into materials of

different densities and elasticities and of different shapes,

complicated equipment is often required to perform the test.

Many techniques are used in the search processes because of

the numerous variables encountered. The ultrasonic beam is

commonly pulsed into the test specimen at frequencies in ex-

cess of 18,000 cycles per second. Cycles below this frequency

may be detected by the human ear; consequently, those higher

than 18,000 are called ultrasonic. The usual testing scale

runs from 20,000 to 25,000,000 cycles per second.

The ultrasonic tewt is becoming more useful because

discontinuities existing at the surface of the test specimen

or those resting deep within the specimen can be identified

through the numerous combinations of inspection techniques.

Because the flaw may be oriented in any directior relative

to the path of the penetrating sound beam, certain principles

must be understood prior to the search. The principle of the

pulse-echo system, for example, is based on reflected sound

from pulsating energy.

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83

Principles of the Test

An examination of these principles can be performed with

illustrations involved in the use of the pulse-echo type unit.

Although each manufacturer designs equipment to his particular

specifications, similar circuitry exists in many models.

Basically, there is a power supply with controls, a trans-

ducer, a couplant, an electrical pulser generator and receiver,

and a display for visual image including some type of timer for

the pulser. A typical ultrasonic testing unit is shown in

Appendix 0.

In order for the ultrasonic wave to penetrate a material,

there must be a means for converting high frequency electrical

impulses into mechanical vibrations. This conversion is ac-

complished by means of a transducer. One of the most common

types of traisducer materials used in obtaining this energy

conversion is the quartz crystal, usually cut on the X axis.

This crystal has piezoelectrical properties; that is, the

ability to transform electrical impulses into mechanical

vibrations and in turn, the ability to receive these vibra-

tions as a signal and change them back into electrical energy.

Appendix P illustrates how the transducer is placed against

the test specimen in preparation for an ultrasonic test.

Energy is also converted by other transducer materials. These

materials include ceramics and lithium sulfate. The ceramic

transducer, lead zirconate titanate for example, is an excel-

lent transmitter of sound energy while lithium sulfate is an

excellent receiver.

88

81+

Testing Techniques

Contact between th1 transducer and the test material is

essential in order that signals will be transmitted. Good

contact materials include grease, oil, and water. The use of

one of these materials acts as a couplant or connector between

the transducer and the test material and assures proper func-

tioning of the transducer. The transducer is used in both

contact testing and immersion testing.

The generation of high energy bursts of electrical energy

come from a thyratron tube which is governed by a timer for

timing the pulses. Because materials vary in density and in

elastic properties, the wave's speed or velocity of travel

through the material is predetermined. Volume or intensity

of the wave determines the maximum distance of vibrations.

As the amplitude changes, the vibrations in the material

become more pronounced because amplitude is the highest point

of the wave and relates to strength of the impulse.

Ultrasonic waves pulse through materials at different

frequencies. When greater depth of penetratic., within the

material is required, the lower frequencies are used. How-

ever, low frequencies do not always detect the discontinuity.

When small discontinuities exist within the Gest specimen,

higher frequencies are needed to identify them, but penetra-

tion is shallow. The wave frequency acts as s ripple moving

into the material. The sound wave compresses matter ahead of

its movement and leaves a less dense area behind it. This

85

ripple or succession of molecular movements occurs as a

stretch away from the energy pulse and then as a quick re-

turn. The lattice network of the material acts as a barrier

to energy penetration. When struck by a burst of energy,

the lino of atoms moves beckwards from a fixed position and

releases the impact to the next line and so on in ripple

form. The elastic nature of the material's molecules then

establishes this tolerance of the shifting action.

When ultrasonic waves are beamed into a homogeneous

material, they move in the direction of the beam's path until

a material differential is contacted or until attenuation

occurs. Collision with the opposite side of the homogeneous

material (material differential) causes the wave to bounce

or reflect back to the transducer. Collision with a discon-

tinuity causes part or all of the wave to reflect back into

the transducer. When a receiver transducer is used in addi-

tion to a transmitting transducer (through transmission), a

loss of energy is indicated when a discontinuity is contacted.

Energy pulses are then relayed to the display unit once they

enter a material.

Signal Characteristics

One of the nost universal devices used in the display of

pulsating energy is the oscilloscope. Because the oscillos-

cope is part of the electronic circuitry, a quick and accuiate

visual presentation of the wave's actions is shown.

90

86

Appendix Q illustrates the presence of a discontinuity in thetest specimen. The.three pips shown on the screen of the

oscilloscope indicate the initial pulse, the discontinuity,and the material's back side reflection. When time becomesa measured distance along the base line of the viewing screen,location of discontinuities is established.

The presence of discontinuities in a material is unknownuntil a test is made. Because discontinuities may rest atany angle relative to the ultrasonic beam's path, severalsearching processes are usually used. When the beam isdirected into the material at 90 degrees from the material'ssurface, a longitudinal beam searches the mass of material.A discontinuity existing within the beam's path acts as abarrier to further penetration and beam energy is reflectedback to the transducer when the pulse-echo process is used.When the discontinuity rests in a plane parallel to the beam'spath, little indication of a discontinuity is reflected; there-fore, a different process should be used to better identifythe flaw. If the transducer is oriented at an angle otherthan 90 degrees from the material's surface, a transverse orshear wave will be beamed into the material at an angle fromthe longitudinal path. Shear waves move slower through mater-ial than longitudinal waves, but are very effective in locatingdiscontinuities beyond the capability of the longitudinalsearch. Should the discontinuity be close to the material'ssurface or be open to the surface, a surface wave can be made

91

67

to ripple across the material by adjusting the transducer to

a steeper angle. The wave may be a lamb or Rayleigh.

The Search Process

An organized coverage of the material's surface is neces-

sary to assure accuracy of the search. Several scanning

processes are used such as the A, B, and C scans. An impor-

tant factor however, associated with the scan is that all

areas of the material be searched. A succession of straight

line passes at intervals across the material provides uniform

scanning and may be accomplished manually by the contact pro-

cess or with automation in which immersion techniques are used.

By varying the searching techniques, the ultrasonic test-

ing and inspection process may be used to locate discontinuities

in any area of the material. The geometry of the material's

shape, the manufacturing process, the chemical analysis of

the material, and other factors such as stress, necessitate

a proper plan of search to assure a valid evaluation of the

condition of the material.

Testing equipment is available for many different test-

ing techniques. Due to the high cost of some models of

ultrasonic equipment, consideration should be given to idhe

types of inspection processes needed. In order that this

equipment be calibrated for proper testing techniques,

special standards or reference blocks are used. These refer-

88

being available from the American Society for Testing and

Materials.

Safety Precautions

Because electricity is the initial source of energy used

in ultrasonic testing, safety precautions pertinent to elec-

trical apparatus must be observed.

Objectives

Objectives of the ultrasonic method of nondestructive

testing are stated below.

I. The trainee should:

A. Understand the principles governing the ultra-

sonic testing and inspection process.

B. Be familiar with the various types of parts which

are commonly tested with ultrasonics.

C. Be aware of the routine procedures involved in

completing the test.

D. Understand the requirements for a specific test

and be able to select the proper test.

E. Understand the advantages and disadvantages of

the test.

F. Understand the forces causing meter indications.

II. The trainee will be able to:

A. Use typical equipment pertinent to ultrasonic

testing.

B. Use the several scan systems.

C. Follow authorized testing procedures.

D. Use the longitudinal, shear, lamb, and Rayleigh

wave techniques.

E. Use the contact and immersion techniques.

8994

90

F. Differentiate among the several discontinuity

indications.

G. Analyze the specific and total situation.

H. Evaluate the total situation.

I. Accept or reject the specific indications.

95

Outline of Key Points

I. Equipment categories

A. 'Operator's ability to use

1. Purposes and principles of equipment types2. Functions of equipment3. Variations to suit needs4. Safety precautions5. Experience in using equipment

B. Purposes of different equipment

1. Particular needs for inspection2. Types and shapes of parts

C. Amplitude and through energy transmission types

1. Discontinuity and beam interception2. Continuous3. Pulsed4. Modulated5. Frequency

D. Amplitude and transit time type

1. Signal amplitude2. Discontinuity location and distance3. Elapsed time4. Frequency, phasing, and pulsing

E. Transducer loading factors

1. Specimen thickness and resonance2. Resonance and impedance

F. Design requirements

1. Inspection needs2. Size, shape, and symmetry of part3. Speed of test requirements

II. Equipment functions

A. Frequency modulation

1. Limitations in testing techniques2. Special applications

9106

B. Continuous oscillator

92

1. Need for this function2. Comparison to other types

C. Time pulsed

1. Source of electrical energy2. Pulsating mechanism3. Echo and elapsed time factors4. Signal (discontinuity) receipt5. CRT display

D. Modulated oscillator

1. Comparison with other units2. Need for this system

E. Resonance

1. Frequency modulations2. Material thickness measurements

F. A-scan systam

1. Cathode ray tube display2. Time-distance-linear factor3. Discontinuity indication4. Back side reflection5. Signal amplitude6. Velocity factors7. Reflected intensity and discontinuity8. Location and size of discontinuity

G. B-scan systam

1. Modified A-scan search2. Interception factors and screen display3. Longer viewing time to study discontinuity

H. C-scan system

1. Visual and written presentations2. Depth problem3. Two dimensional display of discontinuity4. Inclndes features of the A-scan

I. Bridges

1. Manipulation devices2. Circuit patterns

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93

3. Balancing media4. Signal and adjustment capabilities

III. Test systems

A. Through transmission

1. Amplitude relation to discontinuity2. Beam intensities3. Beam transmission through part4. Limited in useS. Energy loss at discontintity

B. Reflected transmission

1. Pulse.-echo principles2. Discontinuity orientation to beam3. Most common technique in testing4. Initial pulse, discontinuity, back reflection5. Elapsed time

C. Single search

1. Reflection testing2. Material coverage from side to side3. Beam interception with discontinuity4. Initial and back side '_ndications5. CRT presentation

D. Double search

1. Two transducer technique2. Common techniques used in Europe

E. Straight beam

1. Transducer face on part2. Flat surfaced parts3. Traditional uses14.. Wear plates5. Beam directed straight from part's surface6. Longitudinal wave

F. Angle beam

1. Beam aimed away from normal angle2. Wedge effects in obtaining angle of beam3. Production of shear and surface waves4. Curved contacts for cylinders

913

G. Generators

94-

1. Variable frequency oscillator2. Very high frequencies3. Continuous input of energy4. Resonance or energy surges5. Battery or conventional line voltage6. Tube generation and pulser

H. Transducers

1. Piezoelectric factors2. Electrical-mechanical and mechanical-electrical3. Mechanical pulsed vibrations into part4. Straight and angle beam types5. Construction materials and shapes6. Uses; through and reflected energy7. Safety precautions

I. Couplants

1. Purpose and principles2. Materials; oils, water, grease3. Uses and efficiency factors4. Types of techniques

J. Indicators and meters

1. Cathode ray tube (CRT)2. Oscilloscope and controls3. Screen displays4. MetersS. Recorders6. Alarms7. Automatic testing systems

IV. Wave propagation

A. Characteristics and principles

1. Mechanical vibrations2. Ultra high frequencies3. Directional travel at velocity4. Time, distance, and attenuationS. Reflection and penetration capabilities

B. Frequencies and ranges

1. Usually from 200,000 to 25,000,000 cyclesper second

2. Geometry and shape of part3. Material of part - elastic nature

99

C. Stress ranges

95

1. High energy levels vs. low stress ranges2. No mechanical damage to parts3. Frequency and magnitudeL. Low amplitude vibrations

D. Wavelenpths

1. Elastic modulus factors2. Waves as fronts in movement3. Velocity and oscillations4. Variables and constants5. Reference tables of wavelengths

E. Vibrations

1. Mechanical from electrical pulse62. Low in amplitude3. Non-damaging to part

F. Velocity

1. Measured in centimeters per second multipliedby a constant

2. As material varies, velocity varies3. Velocity a function mainly of elastic modulus

or density4. Attenuation factors in gas, liquid, and solid5. Motion i3 longitudinal, compound, or transverse

G. Impedance

1. Acoustic impedance factors2. Density times wavelength3. Impedance in various materials

H. Attenuation

1. Energy loss in a material2. Constants3. Difficulty to isolate, yet present4. Penetration capabilities in materials5. Echo time factors6. Noise generation factors

I. Reflection

1. Incidence angles2. Impedance factors3. Time-distance relationships

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96

4. Discontinuity reflection time5. Reflection coefficients6. Transmission coefficients

J. Refraction

1. Incidence of non-normal beam between twodifferent materials

2. Differences in material's sound velocities3. New anglel generated - refracted4- Generation of secondary beams5. Refracted beam intensity

K. Diffraction

1. Diverging effects of beams2. Wave fronts3. Wave interferences4. Beam spreading characteristics5. Need for accuracy in flaw detection6. Discontinuity evaluation factors

L. Dispersion

1. Characteristics2. Energy spread

M. Mode conversion

1. Materials and velocities2. Energy dispersion and propagation3. Surface, shear, and longitudinal waves4. Interception of beam with a different material5. Conversion of one type of wave to another6. Beam spreads7. Conversion factors and effects

N. Special effects

1. Beam spread effects2. Added indications

0. Undesirables

1. False indications2. Variables

V. Testing techniques

A. Contact

97

1. Straight beam longitudinal wave2. Angle beam shear wave3. Surface wave4. Transducer contact with part or wedge use5. Couplants needed6. Pulse-echo transmission7. Through transmission8. Oscilloscope indications

B. Immersion

1. Transducer submerged in water2. Water column or tank3. Submerged test part4. Sound beam path - water to part5. Oscilloscope indications6. Comparisons with contact techniques

VI. Calibration

A. Need for calibration

1. Variable effects2. Transmission accuracy3. Calibration requirements4. Reference blocks

B. Standards

1. Comparisons with standard reference blocks2. Pulse-echo variables3. Types, shapes, and sizes4. Ref..rences for plann'd tests

C. Major parameters

1. Transmission factors2. Transducers3. Couplants4. Materials5. Receiving factors6. Circuitry components and relationships

VII. Defect detection

A. Sensitiveness to reflections

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98

1. Size, type, and location of defect2. Techniques used in detection3. Wave characteristics4. Material and velocity5. Defect orientation to sound beam

B. Resolution processes

1. Standard reference ccmparisons2. History of part3. Probability of type of defect4. Degrees of operator discriminationS. Band width factors6. Frequency effects

C. Energy-noise discrimination

1. Widening characteristics of CRT base line2, Malfunctioning of circuitry3. Irregular patterns and non-cyclic effects.1. Attenuation factors vs. materials5. Probe and coupling factors6. Surface conditions of part7. Refraction factors and effects8. Part geometry and reflections

D. Size of defect determination

1. CRT display and meter indications2. Transducer movement vs. display3. Two-dimensional testing techniques4. Signal patterns

E. Location of defect factors

1. CRT display and meter indications2. Amplitude and linear time3. Search techniques4. Wave forms and scanning areas

F. Kind of defect determination

1. Manufacturing processes relationship2. Heat treating effects3. Chemistry of part4. CRT display5. Scanning techniques

103

VIII. Evaluation

99

A. Defect comparison procedures

1. Standards and references2. Calibration techniques3. Comparison techniques4. Inspection of transducers5. Inspection of amplitude, area, and distance

relationships

B. Object appraisal

1. Part's history in manufacture2. Use of part3. Environment of part in use4. Loading vs. stressing factors5. The stress pattern .4..n reaction6. Type of flaw and location7. Criteria for acceptance or rejection

104

CHAPTER VII

RADIOGRAPHIC TESTING

The radiographic process is the oldest method used in

nondestructive testing. Techniques used in this method are

based on powerful rays of energy penetrating a nass of solid

material and then recording their results on a special type

of film. A homogeneous material to be tested provides for a

uniform penetration of energy, whereas a material containing

discontinuities provides an uneven distribution. When the

rays completely penetrate a material and make contact with a

specially prepared film, a shadow picture of the material's

inside results. This shadow picture is similar to "seeing

through the material." Uneveness of ray distribution results

in light and dark areas on the developed film. Basically,

the criteria for radiographic testing includes a source of

penetrating rays of energy, a part to be inspected, and the

film. The part is placed between the source of energy and

the film.

Characteristics of Radiation

Radiant energy used in radiographic testing includes

the X-ray and gamma ray. Both rays have similar physical

characteristics and they obey the laws of light with regard

to their straight-line paths. These high energy waves are

105)

101

electromagnetic, have no weight, M8,95, or electrical charge,

travel at the speed of light, ionize matter, and expose film.

Their energy is indirectly proportioned to their wavelength

while their penetration power depends on their intensity.

Because matter absorbs these rays, their depth of penetra-

tion is greatly governed by the density and thickness of the

material to be inspected. When thickness of material varies,

results are recorded on the film. Likewise, when density cf

mater1R1 varies (discontinuity), results are recorded on the

film.

Because silver bromide is coated on the thin sheet of

plastic film, exposure to radiation causes black silver to

appear in such proportions (radiation intensity differentials)

that the irmage is outlined with its interior density differ-

ences projected onto the film. In order that the image will

be clear and adequate, a test piece is frequently placed on

the source side of the part to be radiographed. This test

piece, a penetrameter, is usually made of the sAm material

as the specimen to be tested and its geome-rical proportions

are related to the specimen. A satisfactory image of the

penetremeter is evidence of an acceptable technique.

An unusual aspect of radiation is that man's senses cannot

detect it. Man can see ordinary light and follow the trajec-

tory of its expanding beam, but man has no means of "seeing"

the X and gamma rays. However, the ray's effects on man can

be disastrous and deadly when exposure has lasted over a

106

102

period of time. Consequently, zhe process of radiography

includes hazards to health. Personnel who are engaged inradiographic processes must be cognizant of radiation capa-bility and act according to safaty practices recommended bythe Atomic Energy Commission.

Techniques in Radiography

Often, a discontinuity may be suspected deep within a

thick slab of steel. Radiant energy is frequently calledupon to locate this type of flaw. In this respect, two ormore radiographs from different positions will usually showthe location of the flaw when proper techniques are used.As the ray penetrates the thickness of tY metal, ray eb-sorption occurs ahich results in a loss of ray intensity.If intensity is great enough, however, penetration occurs.Should the flaw intercept the radiant beam, a density differ-ential will be reflected on the film. The developed filmwill then indicate light and dark areas whinh portray theimage of the flaw.

Different techniques are necessary for proper productionof radiographs. As the geometry of the part varies, varia-tions in the shadow picture also vary. As an example, whenthe plane of the part and the plane of the film are not par-allel, distortion of the shadow picture will occur and thetrue shape of the part will be lost. Sharpness of the part'simage depends on the distance between the part and the filmand between the part and the source of energy. Also, smaller

107

103

energy sources give sharper images by decreasing the size of

the penumbra. Appendix R illustrates some of these techn:Iques.

Because X and gamma rays diverge as distance from source

increases, greater areas are covered by the rays, but with a

loss of intensity. Consequently, the Inverse Square Law is

used in calculating safety practices and exposure factors,

This means that the beam's intensity varies inversely with

the square of the distance from the energy source and a spread-

ing of the beam occurs much like a beam of visible light.

When an increase in intensity is required, the source's voltage

factor is increased so as to produce rays having shorter wave-

lengths for greater penetration capabilities. However, a

straight-line beam will scatter as it collides with atoms along

the path. Scattering results because of directional changes

from the straight-line path when the collision occurred.

Scattering of beams also results from a part's uneven geometry

and from objects in close proximity to the part being radio-

graphed. Beam scatterinE causes images to be blurred.

Precautions in Radiography

The radiographic method of nondestructive testing

requires special housing for equipment such as a lead lined

room, in order that most of the radiation will be contained

within the room. Room walls may be lead lined or they may

be produced from very thick walls of poured concrete. Because

shielding is often difficult in some instances, soft lead

108

sheets are usually used to absorb most of the radiation in

the area of the source. The density of the lead serves as

a barrier to penetrating radiation. Lead is also very mallea-

ble and can be easily folded into any shape to contain the

radiatiOn if the sheet is thick enough. In these respects,

some radiographic equipment is built within a large lead

lined box in order to remove the major shielding complexities.

These box-like radiographic units can be safely used in a

typically constructed building when their energy outputs re-

main below a specified level. However, radiological checks

from time to time with counters are necessary to assure a

safety zone around the radiation source.

Large pay.ts, on the other hand, require intricate porta-

ble and fixed equipment which demand either a special type

of shielded room capable of containing and absorbing the

radiation or an open area where distance acts as the final

barrier. Because radiography includes the radiation hazard,

all personnel working in a specified radius of the source

must conform to the rules for handling radioactive sources

which are issued by the local, state, and federal governments.

Emission of Penetrating Rays of Energy

The radiographer will be confronted with the need for

X and gamma radiatioL facilities. In these respects, alpha

and beta particles are relatively insignificant, but X and

gamma rays are powerful and penetrating rays. The X-ray is

109

.1.U,

generated within a special electronic tube. A high voltage

input to the cathode provides an abundance of electrons and

as electrons increase in numbers, intensity of the rays

increases. When a high voltage is applied to the tungsten

anode, the negative particles are quickly dral,..1 to the anode.

Because the collisions occur at an angle, much like a billiard

ball's bouncing actions, the particles of energy shoot into

straight-line paths in all directions. The X-ray tube's

shielding prevents radiation from being beamed in unwanted

directions, however, a window in the tube acts as a means

for focusing the source of energy at the target (material to

be inspected). The X-ray can be turned on and off by the radio-

grapher by flipping a switch. The X-ray source is rated in

milliamperes and is directly related to the quantity of free

electrons emitted at the cathode's filament.

The other type of penetrating ray is the gamma ray which

is energy moving away from a decaying radioactive material.

The nuclei of the radiant material constantly disintegrate

and the rate of disintegration is measured in half-life

quantities which is an activity measure. Common isotopes

used in this technique of nondestructive testing are Iridium

192, Thulium 170, and Cobalt 60. These isotopes result from

nuclear bombardment while Cesium 137 is produced by nuclear

fission. Thulium 170 and Iridium 192 are commonly used in

radiography because of their lower energy radiation and their

requirements for less shielding. Cobalt 60, on the other hand,

no

has the equivalent energy emission of an extremely powerful

X-ray machine (mev) whereby thick plates of steel can be

radiographed.

Ray Meaurements

Wavelengths of radioactive materials are determined by

the specific material. Intensity of the gamma ray is measured

in roentgens which means the radiation emitted at a set dis-

tance during a given period of time. In other wolds, the

intensity of energy is measured in roentgens per hour at a set

distance while the measure of energy activity or amount of

scurce energy is measured in curies. Radioactive materiaJs

are contained in lead jugs or pigs. The thick walls of the

lead container absorb and conta-In nearly all of the radiating

energy. Therefore, these containers often become very heavy.

The gamma ray cannot be turned off however, only the contain-

er's window can be adjusted for escape of the rays when

focused on the target.

Because man cannot detect radiation with his senses,

special detection )quipment is required wherever radiation

processes are conducted. An example of detection equipment

includes 'ale baC which is worn by all personnel engaged in

radiographic processes. The badge is measured periodically

to determine exposure of the wearer. A dosimeter is also

carried by the person who works in the radiography area.

This instrument, pencil shaped, indicates the accumulation

of radiation. Another important instrument 13 the Geiger

ifl

107

counter. This counter acts as an alarm in the presence of

radiation and can be used in detecting gross radiant contam-

ination. However, other safety devices must be used when

high radiation intensity is present because of the possible

inaccuracy of the counter at saturation levels of radiation.

Because radiation cannot always be completely confined, the

radiographer (or other personnel) may be exposed to small

quantities. Therefore, all personnel are subject to a per-

missable dose of radiation. This means that the dose of

radiation received should not be harmful during the person's

lifetime. Doses beyond the acceptable amount require sever-

ance from further exposure.

Determine the Source Need

Prior to requisitiol, of radiographic and radiological

equipment, the radiographer should decide on the type of

needed source material. The box type of X-ray apparatus

provides good radiographs within certain limits without the

requirement for a large additional shielding arrangement.

However, this type of installation is severely limited in

energy output and is unsuitable for inspection of large parts.

When increased levels of radiant energ are produced, shield-

ing becomes a necessity. If the gamma ray is needed for

intricate inspections or for deep penetration, the isotope

is used. Either radiographic process requires strict compli-

ance with established codes, rules, and regulations. Appendix

R illustrates a typical box unit for limited radiographic in-

spections. 112

Objectives

Objectives of the radiographic method of nondestructive

testing are stated below.

I. The trainee should:

A. Undertard the principles governing the radio-

graphic testing process.

B. Be familiar with the various types of parts

which are commonly inspected with radiation.

C. Be cognizant of the routine procedures involved

in accomplishing the test.

D. Understand the requirements for a specific tech-

nique and be able to select the technique.

E. Understand the advantages and disadvantages of

the test.

F. Understand and be familiar with the safety pre-

cautions pertinent to radiation hazards.

II. The trainee will be able to:

A. Use typical equipment peculiar to radiographic

processes. Use should be confined to the softer ray tests

unless special requiremente dictate otherwise.

B. Comply with local, state, and federal radiation

safety codes.

C. Use the attachments and accessories pertinent

to routine testing.

11:3108

109

D. Use the X-ray technique in locating discontin-

uities.

E. Use the gamma ray technique when this teohnique

is required.

Note: The trainee should be familiarized with the

gamma ray test and should be given the opportunity to perform

some of these tests.

F. Differentiate among the several patterns of

discontinuities.

G. Analyze the specific and total situation.

H. Evaluate the total inspection situation.

I. Accept or reject the specific indications.

114

Outline of Koy Points

I. Equipment

A. Operator's ability to use

1. The X and gamma ray principles2. Purpose and objectives of tests3. Safety precautions4. Safety code compliances5. Operational techniques6. Experience in equipment use

B. Purpose of types

1. Purpose of test2. Objectives to be obtained3. Fixed and mobile types

C. Fixed installations

1. Self shielded2. Semi-mobile3. Higher energy systems4. Special designs5. Large and heavy parts

D. Mobile types

1. Mobility needs2. Shielding factors3. Special designs

E. X-ray tyPe

1. Low energy machine2. 150 KV machines (possible limit of low energy)3. High and very high voltage machines4. Shielding factors and codes5. Safety precautions6. Radiation detection devices7. Inspection needs

F. Gamma ray type

1. Common isotopes2. Curie factors and source shape

110

115

3. Shielding nees and problemsI. Safety precautions and codes5. Radiation detection devices6. Inspection needs7. Decay factors and cost

G. Design requirements

1. Inspection needs2. Part geometry3. Shielding requirements

H. Safety precautions and practices

1. Local, state, and federal codes2. Manufacturers'codes and specifications3. Atomic Energy Commission codes4. Amovican Society for Testing and Materials codes

American Society for Nondestructive Testing codesInterstate Commerce Comml.svion codes

7. Shielding and radiation detection factors8. Exposure values9. Radiological equipment

II. Radiation

A. Principles

1. X-ray sources2. Gamma ray sources3. Intensity and strength factors4. Materials impervious to radiation5. Existence factors

B. Types of rays

1. X-rays2. Alpha and beta rays3. Gamma rays

C. Electroniv! sources

1. The X-ray tube2. Cathode-anode arrangements3. Electron flow and quantity4. Anode potentialS. Deflection pattern6. Window and shadow picture7. Shielding8. On and off existence of source9. Penetration capabilities

116

D. Isotopic sources

112

1. Radioactive material::2. Half life values of isotopes3. Decay phenomena4. Alpha, beta, and gamna ray emissions5. Curie factors and effects6. Roentgen factors and effects7. Shielding needs8. Intensity focus control9. Penetration capabilities

10. Cannot turn rays off

E. Sensitivity

1. Insensity factors and energy levels2. Velocity3. Source to film distance4. Part to film distance

F. Intensity distribution

1. Quantity of electrons2. Voltage variables3. Electron acce1ation4. Current and filament temperature5. Anode voltage6. Intensity in milliamperes

G. Detection devices

1. Badges for wear2. Dosimeters3. Geiger countersk. Radiological safety s'tandards

H. Handling proceaurri

1. Known energy levels2. Shielding uses and requirements3. Curie and rcantgen factors4. Ra7 focus, beam spread, and scatteringS. Distance factors vs. energy levels

I. Primary effects

1. Penetration,and ionization u rects2. Spread and scatter variables3. Abs.orption characteristics4. Film exposure effects5. Human exposure and dose levels

117

113

J. Secondary effecto

1. Exposure factozio2. Molecular change potentials

K. Shielding procedures

1. X-ray and gamma ray requirements2. Machine source existence of ray3. Area shielding needs and specifications4. Container thickness and access window5. Window control of different rays6. Code requirements

L. Absorption characteristics

1. Molecular crystalline structure2. Density faci,ors3. Thickness of shielding values4. Shielding materials5. Molecular collision patterns6. Radiation efft.cts on materialb

M. Scater effects

1. lc,ternal nature of ray path and divergence2. iart geometry and side effects3. Near-by object influences

N. Pair production

1. Limited to extremstly high energy levels2. Electromagnetic radiation collisions with atom3. Radiant energy conversion4. Positron and electron pair5. Collision path and convergence6. Additional effects of pair uniting

0. Protection and safety codes

1. Radiological monitoring criteria and standards2. Area detection and alarm devices3. Local, state, and federal codes4. Professional organization codes and specifications

P. Radiatior dose control

1. Radiation measurement2. Human dosc, accumulation3. Maximum permissable dose4. Atomic Energy Commission Guides

118

5. Time and distance factors6. Exposure factors7. Construction techniques for protecion8. Permissible levels of radiation9. The radiation survey team

10. Radiological testing and monitoring11. Instrument and device protection

III. Procedures

A. Shadow picture and geometry

1. Radiation source2. Size of source and shape (gamms.3. Focal spot and distanceL. Part geometry5. The image-source triangle6 Image sharpnesz,7. Penumbra8. Distortion effects and characteristics

B. Focal spot and window

1. Geometry of ray travels2. Intensity and projection characteristics3. Source size and shape (gamma)4. Rectangular opening of X-ray window5. Angle of electron.collision at anode6. Actual &Lid effective focal spots7. Temperature factor, anode material and focus

C. Electromagnetic waves

1. Gamma ray and X-ray characteristics2. Applications of the laws of white light3. Absence of mass and electrical chprge4. Wavelengtn vs. energy5. Human senses cannot &,.tect6. Ionization of matter capability7- Film exposure capability8. Matter penetration capability9. Discontinuity in material detection

D. Techniques

1. Conventional radiographic procdures2. Stereoradiography

::eroradiography4. Fluoroscopy

E. Voltage and amperage factors

1. Line voltage and input to X-ray machine2. Transformer action3. CircuitryL. X-ray tube and shielding5. Current and voltage input

Cathode current7. Anode voltage8. Milliampere ratings

F. Exposure factors and contrast

1. Time of exposure and radiation intensity2. Radiation intensity differences in a material3. Homogeneous materials'affects

G, Screens and filters

1. Material types for screens2. Purpose and principles of screens3. Lead alloys and fluorescent materials4. Filter materials5. Prirciples of filtering6. Abs.)rbing characteristics

H. Film characteristics and types

1. Film structure and chemical content2. Purpose of silver bromide3. Radiation and film exposureL. Use of penetrameters5. Contrast effects and functions6. Types7. Techniques in radiography8. Film holdo::5;9. Dark room p-:ocedures and processing

10. Dark room equipment

I. Laws and rules

1. Physics of X and gamma rays2. Penetration capabilities in solid materials3. Matter response to radiation4. Safety observance and precautions5. Shielding vs. exposure6. Life and health hazards7. Governing codes

120

J. Object material and density

1. Physical constants of elements2. Velocity vs. density3. Penetration vs. density4. Thick-aess and penetration

K. Image quality factors

1. Sharpness of part image2. Source-part-film distance relationships3. Geometry of planes during exposure4. Distortion faccors5. Contrast effects

L. Penetrameters

1. Image clarity testing2. Purpose of penetrameters3. Geometry of penetrameters4. Materials

M. Film processing

1. Po,:ential image after eposue to radiation2. Sequential procedures3. Equipment in the dark room4. DevelopingS. Neutralizing of developer6. Excess silver bromide removal7. Water washing and drying

IV. Evaluation techniques

A. Criteria for evaluation

1. Objectives of tests2. Standards and references3. Penetrametersk. Comparisons

B. Defect identification

1. Standards for comparison2. Image clarity and shadow picture3. Contrast and completeness4. Types of discontinuities5. Shapes and sizes of discontinuities6. Location of discontinuities

121

C. Appraisal of object

1. History of part2. Loading fatItors and stress3. Use of part4. Location of discontinuity5. Acceptance and rejection criteria

k;HAFTER VIII

OTHER NONDESTRUCTIVE TESTING METHODS

The five main methods oe nondestructive testing provide

the majority of tests needed in quality control of man-Afac-

tured parts. However, there are sev,-al additional tests

which provide a greater coverage for _1 total manufacturing

process. These additional methods are summarized below.

Magnetic Rubber Test

A prepared mixture of ferrous powder and liquid rubber

can be used to supplement the magnetic particle test. When

the liquid mixture is placed and held in contact with a ferrous

area, that appears receptive for discontinuities, in the pres-

ence of a magnetizing current (pmds), the ferrous powder and

syrup are attracted into the discontinuity. The principle is

very simil. .r to the north-south pole relationship of magnetic

inspection. Because the syrup encloses the area to be inspect-

ed, any discontinuities will immediately absorb the syrup due to

the polar condition. This polar environment then attracts the

syrup deeply into any discontinuity or irregularity which is

in proximit- of the syrup.

The electrical pr,Jus are placed on each side of the

suspected area and the ar a between th3 prod:: then becomes

the inspection zone. The current is allowed to flow until a

.410.1_4 t3

119

good flux is established. In turn, the syrup enters all

discontinuities, remaining in the discontinuity until solid-

ification of the syrup occurs. When solid rubber forms, it

is then removed and examined under a microscope (low magr-'-

fIcation) for ulleven &yeas and other clues which. may be

indicative of discontinuities.

The magnetic rubber test is ideal as a supplement to

eddy current testing techniques, but may often be used as

the primary test. Holes and corners of ferrous parts are

ideal areas for inspection by this teat.

Infrared Test

This nondestructive testing .7)thod provides inspection

of materials by use of the infrared heat principle. When the

source Of energy is focused across the part to be inspec ad,

a pattern of heat absorption occurs in the material. Homo-

geneous material will provide a uniform indication of heat

absorption. This indication, through electronlc c litry,

is relayed to a meter or an oscilloscope. As long as sound

material is contacted, a uniform signal will be established.

However, when a discontinuity is contacted, a temperature

differential exists at the discontinuity and this differen-

tial is then displayed at the meter or oscilloscope. The

oscillozcopels base line, in this case, on the screen can

be arranged to present the discontinuity in two-dimensional

shape.

120

The two basic infrared testing systems include thepointing radiometer, for line, scanning, and the raster scan-ning type. The heat generated requires control; therefore,air iE normally used to cool the pointing

radiometer whileliquid nitrogen is used in the raster type. Because thesetypes of inspection devices are often used for inspectingparts where different materials make up the assembly, theaircraft industry finds them advantageous. Assemblier suchas bonded laminations are inspected by this process.

Acoustic Emission Testdhen parts are highly stressed and discontinuities beginto form, a reflection of the metal's separation sound patternis detectable in the acoustic emission, testing process.

CraL:ks especially are detectable during the process of metalfailure Research has shawn that the noise generated bythe separating metal is indicative of a stress factor. Asstress increases and decreases, noise changes its pitch andbecause of its containment,

reflects itself repetitiouslywithin the material.

Emission noises are sound frequencies and are detectedby the transducer. Because of containment in the material,a varying pitch results. The frequency variation apparentlyis loudest from the crack and yeakest from very small irreg-ularities. As a mterial is stressed and the discontinuityexpands, emission also increases. As a crack, for example,

125

121

begins to increase, emission increases an appreciable amount

to the failing point.

The acoustic emission process of nondestructive testing

is in the stage of further development. Tests have shown

that grain pattern and oti-er microstruc.t,ural factors influ-

ence the emissions. From an operational point of view, this

process has tremendous potentials in that emissions are

warnings.

Other Techniques Used in Nondestructive Testing

Electrical systems variations

Electromagnetic ray varitions

Frequency variations

Heat variations

Holographic

A..aser

Light variations

Optics and visual ezlaminations

Photoelastic stress cycling

Sonic

Strain systems

Vibrational

126

CHAPTER IX

CURRICULUM

This proposed curriculum for training nondestructive

testing and inspection technicians is the rerult of an

intensive search for information. Contents of this curricu-

lum have been extracted from data obtained in a statewide

industrial survey.

The key points in each of the fiv main methods of

nondestructive testing end inspection have been outlined in

previous chapters. Edw. onal objectives have also been

stated for each of the five; methods. The five main methods

of testing comprise the core of the curriculum, but this core

must be supported with foundation EAcills and knowledge.

Together, the foundation and the core skills are needed to

build the complete curr:i.culum.

Foundation Anowledge and skill provide for understanding

the principles of the core skills. A listing of this founda-

tion subject matter, general education, is shown in Appendix S.

These eighteen subjects, when integrated into the total program,

should help provide a high level of proficiency in bhe graduate.

An examination of the core skills shows that electricity,

metallurgy, and mathematics comprise the bulk of the knowledge

needed in conducting the main methods of testing. Therefore,

122

127

123

these subjects should be weighed heavily in the overall train-

ing program.

An examination of the subject matter shown in each of

tha five main outlines of key points, together with the sub-

ject matter listed in Appendix S, indicates that most of these

subjects can be integrated into less than a dozen specific

subjects. Specifically, a training program comprising a dozen

technical subjects, supported with a few general educational

subjects, will provide the backbone of the curriculum.

After reviewing all data obtained from Part I of this

study, it is recommended that a minimum of four semesters be

established as the general time requirement for the proposed

program. In order to allow for a minimum of general education,

the proposed program should consist of seventy-four semester

hours of specified subject matter. Because some subjects re-

quire prerequisites, a basic and an advanced couree will be

needed in some areas. Each of the twenty-five subjects shown

in the curriculum below must then be patterned to include the

knowledge, principles, procedures, and related information

necessary to guide the trainee to graduation as a nondestruc-

tive testing and inspection technician.

In order to allow for theory and application of theory,

technical subjects will be divided into lecture and labora-

tory periods. Experience has shown, in technical subject

areas, that approximately three clock hours of laboratory

experience will allow the trainee enough time to apply the

128

124

principles he learned in the two clock hours of discussion.

Also, the five clock hours, extended over a semester, will

provide a comprehensive coverage of the area to be covered.

Because a hierarchy of subjects must be provided, from

beginning to graduation, a sequence is therefore established.

The recommended curriculum in support of this program is

shown below. However, flexibility must exist within the two-

year period; therefore, subjects may be taken at a time best

suited for the trainee, provided he has the prerequisites. A

description of each course shown in the curriculum is also

provided below.

Even though course descriptions are very general in

coverage, the description does include the scope of instruc-

tion. In order to ascertain the detailed coverage of each

course, the syllabus must be reviewed. In this respect,

course planners must give due consideration to proper course

coverage by verification that all needed subject items ror

the course are shown in the syllabus. In effect, reference

should be made to previous chapters of this study to assure all

needed items are included in the syllabus. It is not intended,

however, that previously outlined key points of instruction be

all inclusive. The instructor should use his best judgement

in organizing his program.

Due to flexibility in industrial needs, some kinds of

industry may require the technician to be cognizant of tech-

nical information that is not shown in the proposed training

129

125

outlines. Research has shown that additional knowledge may

be required for some technicians, depending on che manufac-

turer's needs. Tnese additional possible needs are shown

in Appendix T. These subjects may be added to proposed

programs wherever required.

Curriculum planners must also be aware of the tremendous

spread of American manufacturing capability. A training pro-

gram for an aircraft plant will be different from that needed

in a shipbuilding yard. Even though basic principles and

procedures apply to programs, specific needs may necessitate

curriculum changes. For planning purposes, some of the

-.ranches of industry using nondestractive testing processes

are shown in Appendix U.

Also, it is interesting to realize the high percentage

of manufacturers who recommended nondestructive testing for

inclusion in other technology training programs. Appendix V

lists seventeen technologies that were recommended to include

some form of nondestructive testing processes. This study

has shown (Part I) that 70 per cent of respondents queried,

indicated that seventeen separate technologies should be

supported with some form of instruction 5n nondestructive

testing. The listing indicates results obtained from the

industrial survey. Metallurgical technology was checked by

85.8 per cent of the respondents as needing tbis instruction

the most, while Electronics technology was checked by

per cent as needing this instruc;:ion the least. From these

130

126

statistics, it is evident that a large percentage of the

metal manufacturing industries (other than low stressed

parts) have sortie form of nondestructive testing in their

production line:a.

Another consideration during the curriculum planning

phase must inclUde a sharp and continuous look at the total

program. Such things as field trips and factory familiariza-

tion visits shoUld be included in programs whenever feasible.

As an example, Many training programs will probably not in-

clude gamma radiation testing facilities. In this respect,

a visit to a radiation laboratory will make a fine substi-

tute. A short factory indoctrination visit may also provide

insight into a specific area of learning.

Reference should be made to the equipment listing in

this guide, Appendix W, as an e litional source of learning

aids. Many manufacturers prod- and provide numerous bro-

chures pertaining to specific ms of testing equipment. A

supply of these brochures can nd vitbaity and realic.y to a

program. In triis respect, expfience is a wonderful teacher;

therefore, equipment should be usd as much as possible in

order to learn the testing process.

Appendix W provides a listing of equipment that has been

recommended by several manufacturers for use in training non-

destructive testing and inspection technicians. This listing

provides several choices in the same types of equipment and

imiudes units for use in all areas of nondestructive testing.

131

127

Obviously, there are many types of equipment not listed due

to the impracticability of publishing a large volume of items.

It is recommended that course planners contact the manufacturer

and obtain brochures pertinent to specific types of equipment

prior to requisitioning.

Due to the high cost of equipment, it is recommended

that the laboratory group of trainees be divided into sections

and then rotated through each method of testing. Once the

basic principles of the several tests are larned, rotation

can be ac:complished in an effective manner. Appendix X

suggests a typical laboratory arrangement.

132

PROPO SED CURRICULUM

in

NON DESTRUCT IVE TESTING

133

128

129

Nondestructive Testing Technology

Curriculum

First.Year

First Semester Credit Lecture Lab

3 03 32 32 32 31 2

13 17'

Applied Communications I 3Applied Physics and Mathematics 1 4Basic Principles of Nondestructive Testing 3.Manufacturing Materials and Processes I 3Metrology 1

Physical Education 117

Second Semester

Applied Communications II 3 3 0

Applied Physics and Mathematics II 4 3 3Manufacturing Materials )zid Processes II 3 2 3

Basic Electronics 3 2 3

Applied Penetrant and Magnetic Particle Testing 3 2 3

Physical Education 1 1 217 13- 14--

Summer

United States GovernmentTexas State and Local Government

Second Year

3

First Semester

Applied Physics and Mathematics III 4Basic Radiography in Nondestructive Testing 3Basic Ultrasonic Nondestructive Testing 3Introduction to Quality Coatrol 3Strength of Materials 3

7:6-

Second Semester

Industrial Psychology 3Advanced hadiography in Nondestructive Testing 3Advanced Ultrasonic Nondestructive Testing 3Inspection Standards 3Practical Problems in Nondestructive Testing 3Eddy Current Testing

Total Semester Hours: 714134

3 0

0

3 33 02 32 32

12...1.__

12

3 02 32 32,..-.)

33

3 2 3TEr 13 i5r-

130

Applied Communications I. (3-3-0). Language study

involving grammar, punctuation, and spelling skills

with frequent exercises in the developmnt of

accurate and precise sentences and paragraphs.

Emphasis on composition is given in the area of

practical application.

Prerequisite: A grade of C or better in Developmental

English or equivalent, or satisfactory score on

placement test.

Applied Physics and Mathematics I. (4-3-3). A basie

course for occupationel programs including whole numbers,

fractions, decimals, units, exponents, operationR1

algebra, stated problems and geometry. Applications

are made utilizing the slide rule and calculator.

Laboratory fee charged.

Basic Principles of Nondestructive Testing. (3-2-3).

This is a basic course which investigates the purposes,

principles, and main methods of nondestructive testing.

Also studied will be the origin and significance of

discontinuities in manufactured parts.

Manufacturing,Materials and Proceszes 1. (3-2-3). This

is a study of the various materials used in the metals

and plastics industries. The course is designed to

familiarize the student with the several materials used

in manufacturing and to acquaint him with the chemical,

physical, and mechanical properties of these materials.

135

131

A study of the various types of manufactured parts will

be acc-Implished. Laboratory fee charged.

Metrology. (3-2-3). This course is designed to provide

proficiency in the use of standard measuring tools,

fixtures, and instruments in support of inspection

activities during manufacturing procesaes. Techniques

for achieving accurate measurements will be investigated

to include the use of standards and references.

Health Conce ts of Ph sical Activity, (1-1-2).

A general course in college physical education designed

to teach the biophysical values of muscular activity

through lecture and laboratory periods. In the laboratory

periods, a swimming proficiency test and a physical

fitness test are given to determine the student's future

physical education program. Required for full time,

first semester freshman. Laboratory fee charged.

Applied Communications II. (3-3-0). Composition slanted

toward writing technIcal reports, brochures, promotional

materials, surveys, and similar projects. Attention will

be given to the preparation and delivery of speeches

pertaining to technical or business interest.

Prerequisite: Applied Communications I.

Appli.Bd Physics and Mathematics II. (4-3-3).

Topics covered are review of operaWnal algebra, coor-

dinate geometry, vectors, trigonometry, statics, forces,

quadratic equations, heat and properties of matter.

136

132

Applications are made in demonstrations and laboratory.

Labxoatory fee charged.

Prerequisite: Physics and Mathemeties I cr equivalent.

Manufacturing Materiala and Processes II. (3-2-3).

Fundamental and advanced manufacturing processes will

be discussed including the processing of materials

through the various stages of production. Testing,

inspection, and quality control procedures will be

accomplished. Laboratory fee charged.

Prerequisite: Manufacturing Materials and Processes I.

Applied Penetrant and Magnetic Particle 7,9_AIing... (3-2-3).

Included in this course is practice in penetrant and

magnetic particle testing principles, procedures,

applications, and capabilities. Students will be

familarized with the use of equipment and accessories

relative to these testing methods.

Poerequisite: Basic Principles of Nondestructive Testing.

Physical Education. (1-1-2) A Continuation of Physical

Education I.

Basf_c Electronics. (3-2-3). This is a beginning course

in eleci,ronics and includes the fundamental principles

of direct and alternating currents used in typical

electronic circuitry. Special emphasis will be given

to circuitry principles involved in the use of nondes-

tructive testing equipment such as magnetizing currents,

eddy currents, transducers, and X-ray circuits.

133

United States Government. (3-3-0). United States

constitutional and governmental systems are studied

for the purpose of understanding good citizen attributes.

Texas State and Loc;a1 Government. (3-3-0). Texas

state, county, and municipal governments are investi-

gated and contrasted with other states in the union.

Applied Physics and Mathematics III. (L4.-3-3).

Continuation of Physical Science II with emphasis on

trigonometry, solutions to equations, complex numbers,

radicals, logarithms, energy and motion, electricity

and circuits. Applications are made in demonstration

and laboratory. Laboratory fee chargnd.

Prerequisite: Physics and Mathematics II or equivalent.

Radiography in Nondestructive Testing. (3-3-0).

iuction to Radiogr-ohy theory is studied, including

discussions and demonstrations. Field trips to

industrial X-ray and gamma ray laboratories will be

accomplished. Course covers fundamentals of radiation

safety and prote-tion; radiation measurement doses,

exposure factors and biological effects; instrumentation

and basic equipment used in X-ray and Isotope Radiography;

requirements of state and federal regulations; and basic

radiographic and radiological techniques.

Prerequisite: Basic Principles of Nondestructive Testing,

Manufacturing Materials and Processes II, and Basic

Electronics.

1314.

Basic Ultrasonic Nondestructive Testing.. (3-2-3).

This is a laboratory course which includes basic

ultrasonic testing prirtr3iples, procedureJ, applications,

and search capabilities. Equipment will be used to

explore the several testing techniques. Calibration of

test units will be included.

Prerequisite: Basic Principles of Nondestructive

Testing, Manufacturing Materials and Processes II,

and Basic Electronics.

Introduction to Quality Control. (3-2-3). This study

provides an investigation into manufacturing processes

with a view toward quality assurance and reliability

through management, nondestructive and destructive

testing techniques, and statistical control procedures.

Prerequisite: Basic Principles of Nondestructive

Testing and Manufacturing Materials and Processes II.

Strength of Materials. (3-2-3). This 5s a study of

the several mechanical properties of materials. The

course is intended to provide technical and design

students with a basic undexItanding of strength of

materials as related to parts designed. Included in

this study will be relationships among materials,

loads, and stresses pertaining to parts manufactured by

means of casting, forming, welding, and machining

processes. Laboratory work includes material inspection

and the use of testing equipment. Laboratory fee charged.

Prerequisite: Manufacturing Materials and Processes II

and Applied Physics and Mathematics II.

135

Industrial Psychology. (3-3-0). This is a study of

industrial organization and management, line and

staff functions, employee-employer relations, control

techniques, labor-management policy and procedure,

effective supervision, and industrial planning. This

course is also designed to assist the student to make

the adjustment from college to employment.

Advanced Radiography in Nondestructive Testing.. (3-2-3).

This course is designed as a continuation of basic

radiography and includes theory of radiographic image

formation, exposure calculation, radiographic techniques,

darkroom procedures, and film reading. Procedures are

accomplished in advanced radiography including the use

of X-rays and isotopes applicable to various materials

and situations.

Prerequisite: Basic Radiography in Nondestructive Testing.

Advanced Ultrasonic Nondestruct'-,' T ,ng. (3-2-3).

Advanced ultrasonic theory ana I, sting techniques will

be investigated for the purpose of illustrating the use

of equipment in flaw detection processes. Both contact

and immersion testing systems will be studied to include

the use of the several wave searching techniques.

Prerequisite: Basic Ultrasonic Nondestructive Testing.

Inspection Standards. (3-2-3). Included in this course

will be a review of inspection standards related to

manufacturing processes and quality assurance, including

136

a survey of pertinent specifications. Inspection tools,

gages, instruments, and mechanisms will be used in

illustrating the need for .7.aintaining quality control

in industry.

Practical Problems in Nondestructive Testing. (3-2-3).

This is a laboratory problems course involving the use

of the main methods of nondestructive testing in the

search for discontinuities. Problems are related to

typical manufacturing processes.

Prerequisite: Course or experience in Penetrant,

Magnetic Particle, EddT Current, Ultrasonic, and

Radiographic testing 1,-thods or permission of instructor.

Eddy Current Testing.. (3-2-3). This is a study of eddy

current principles an-4 electrical concepts related to

nondestructive testir Included in this study will be

eddy cv,Irrent testing techniques to include conductivity

measurements and discontiluity and thickness testing.

Also, phase and modulation ar .A_ysis will be investigated

along with special applications.

Prerequisite: Introduction to Basic Principles of

Nondestructive Testing, Manufacturing and Materials

Processes II, and Basic Electronics.

141

APPENDIX

Appendix Page

A. Typical Parts That Are Tested ByNDT Processes 139

B. Typical Discontinuities 141

C. The Stress Pattern and Discontinuities . 142

D. Discontinuities in the Ingot 143

E. Flattened and Elongated Discontinuities. . 144

F. Heat Treating Cracks 145

Fl. Steel Microstructures 146

G. Fatigue Crack in Beam 147

Gl. Fatigue Crack at Surface 148

H. Checks in Ground Part 149

Hl. Design Crack 150

I. Forging Laps and Cracks 151

J. Discontinuities in Welds 152

K. Liquid Penetrant Testing Unit 153

L. Magnetic Particle Tester 154

Ll. Magnetic Particle Inspection 154A

L2. Magnetic Particle Inspection 1,55

M. Eddy Current Coil 156

N. Eddy Current Tester 157

Nl. Eddy Current Tester 158

0. Ultrs-onic Tester 159

137142

138

Appendix

01. Ultrasonic Test Unit

02. Ultrasonic Test Standards

P. Transducers and Waves

Q. Oscilloscope Picture of Discontinuity

Page

160

161

162

164

R. Box Type X-Pay Unit 165

S. General Education Subject Matter 166

T. Additional Subject Matter Recommendedin the Training of NET Technicians. 167

U. Branches of Industry That Are Supportedwith Nondestructive TestingProcesses 168

V. Technologies Recommended for Instructionin / idestructive Testing 170

W. Nondestructive Testing Equipment 171

Wl. NET Equipment Manufacturers 181

X. Laboratory Arrangement 183

143

APPENDIX A

TYPICAL PARTS THAT ARE TESTED BY NDT PROCESSES*

Agricultural ToolsAircraft PartsArborsArmor PlateArmsAssemblies and Sub-AssembliesAutomotive Stressed PartkAxlesBarsBeamsBearingsBedsBilletsBladesBloomsBoiler PartsBoltsBoxesBracketsBrazed FittingsBulkheadsBusses - Stressed PqrtCamp.tdalinonCastings - All TypesCeramics - Powder MetallurgyChainClampColumnsCompressor PartsConduitsConnectorsContainersControlsCouplingsCrankshaftsCuttersCylindersDiesDiscsDrives

13'144

DuctsElectrical FittingsElectronic FittingsEngine BlocksExtensionsExtrusionsFlangesFoilsForgingsForksFormed PartsFlywheelsGearsGuidesGunsHandlesHingesHoles - SurfacesHoneycombHousingsHydraulic Fittings1mi F7rtsIng.)tsInstrument PartsJoints - All TypesKeyrKaysKnia4lkesLiraageLongeronsMachi:lery - All TypesMechanisms - All TypesMiarostructuresMiasdlesMommt.sMumationsNutz,Or_ticesPimmPipePisdol Parts

114-0

APPENDIX A --Continued

Pistons ToolsPlastics - All Types TrunnionsPlate TubingPressure Containers TurbinesProjectiles ValvesPropellers WashersPulleys WaysPump WeldsPunches WheelsRaceways WireRacks drenchesRailroad Locomotive Parts

and Cars .

RailsRamsRetainersRifle PartsRingsRivetsRockersRodsRollersRotorsSawsScrewsSeatsShaftingSheetShip PartsShoes - MachinerySlidesSoldered FittingsSolid MaterialsSpace HardwareSpace VehiclesSpacersSparsSplinesSpokesSpindlesSpringsSprocketsSteering PartsStressed Fittings - AllStringersSupports

*Inspections depend on degree of use, stress, safety,and cost. Highly stressed parts are inspected byNET processes.

145

APPENDIX B

TYPICAL DISCONTINUITIES

110I

tNIV

OM

IMM

MO

VO

...1.

1ms.

..-M

a

qui

4.51

11.

fga

g.D

cc"h

erM

M.

r

141

ASurface crack

FPipe

BBlow hole

GPorosity

CCavity, internal

HInclusion

DInclusion, internal

IIngot

EInclusion

APPENDIX C

THE STRESS PATTERN AND DISCONTINUITIES

AStress, internal flow

BStress concentration

CDiscontinuity

APPENDIX D

LACONTINUITIES IN THE INGOT

APipe

BPorosity

CCrop line

DScrap

ETo be rolled

FCast - coarse grain

v.;

(as cast)

Microscopic view

G Rolled (as rolled)

41

Microscopic view

CO

Grain boundary overlaps

WROUGHT

CA

ST

GRAIN

\BO

UN

DA

RY

APPENDIX E

FLATTENED AND ELONGATED DISCONTINUITIES

AInclusion, flattened

B Inclusion, elongated

CDirection of rolling

DSteel plate

APPENDIX F

HEAT TREATING CRACKS

A,B,C

Quench cracks

Microstructure, 500 X Martensite

(Section removed)

Reamer

FStress was greater than strength

G Rockwell C 63 (satisfactory)

Cracks resulted from overstress

Tool must be scrapped

APPENDIX F -- Continued

SEA

MS

ASeam in pipe

BSeam in rod from which reamer was made

APPENDIX F-1

STE

EL

MIC

RO

STR

UC

TU

RE

S

A Ferrite, 500 X

BPearlite, 500 X RB 82

CMartensitel 500 X RC 64

D Coarse Rrain

ESeam, inherent from ingot

FFine grain

GRolled from ingot stock

APPENDIX G

FATIGUE CRACK IN BEAM

ALoad, variable

ECompression stress

B Beam

CColumn

D Fatigue crack

Resulted from cyclic loads at A,

from no load to load to no load,

etc.

Failure rests ahead

13

FTensile stress

APPENDIX H

CHECKS IN GROUND PART

fA

t

AChecks (cracks)

Bar was surface ground; checks appeared while and after grinding

ACrack - Unevenmass and 90

degree corner with no

fillet

BIntergranular crack, 200X

APPENDIX H-1

DESIGN CRACK

C, Intragranular crack, 20(

D Hardened steel,

martensite, RC 64

APPENDIX I'

FORGING LAPS AND

CRACKS

ALap, oxide caught

between

BBurst, surface

CCracks

D Burst, internal

layers

of metal

APPENDIX J

DISCONTINUITIES IN WELDS

AInclusion

EStar crack

ILack of fusion

BPorosity

FLack of penetration

JWeld zone

CUndercut

GSurface inclusion

KBead

DTransverse crack

HLongitudinal crack

LFusion zone crack

MScale or slag

APP

DT

DIX

K

LIQ

VID

PENETRANT TESTING UNIT*

.ta

rn,

ABench

EWashing

IVisual inspection

BBench

FExamination

JFinal inspection

CPenetrant tank

GDrying

K Black light

DDrain

HDeveloper

*Locally manufactured

LCrack (black light)

APPENDIX L

MAGNETIC PARTICLE TESTER

ACurrent flow

B Flux

CInspection liquid

D Crack

E Part

Part holder

Electric cable

Circular

Longitudinal

Magnetic particle tester

31

t.)

I

A Flaw in part

Al Eddy current detours

around crack

B Part to be inspected

CInstrument

D AC source, coil wire

E Eddy current enil

FCable from test unit to

coil

APPENDIX M

EDDY CURRENT COIL

(Schematic)

II

11

1I

01

iI

1

1,11.110

1f00,11

7

'

k,

'0

n

-..--.E-

APP

EN

DIX

P

TRANSDUCERS AND WAVES*

*Continued

163

APPENDIX P --Continued

A Oscilloscope picture and pips

Al Initial impulse

A2 Discontinuity

A3 Back side reflection

B Transducer (ultrasonic)

C Wedge

D Longitudinal wave

E Shear wave

F Surface wave

G Discontinuity

H Part to be insnected

I Couplant

J Cable from unit to transducer

330

APPENDIX Q

OSCILLOSCOPE PICTURE OF DISCONTINUITY

AOscilloscope pips

Al Initial ultrasonic impulse.

A2 Discontinuity

A3 Back reflection

B Transducer

CCouplant

D Longitudinal beam wave

CABLE

E Discontinuity

FPart to be inspected

A3

APPENDIX R--continued

ASource of radiation

B Part

CDiscontinuity

D Film

E Dark areas on film

FPart and film distance

GPart and source distance

HRay lines enclose mass

differential only; other

areas of part will show

on film as lighter areas

APPENDIX S

GENERAL EDUCATION SUBJECT MATTER

Oral communication

Technical writing

Fundamentals of physics

Industrial chemistry

Fundamentals of electronics

Applied electronics

Applied algebra

Applied geometry

Applied trigonometry

Quality control

Metrology

Basic statistics

Manufacturing pi.ocesses

Basic metallurgy

Heat treatment of metals

Specifications and standards

Operator equipment maintenance

Safety precautions

166

174

APPENDIX T

ADDITIONAL SUBJECT MATTER RECOMNENDED

IN THE TRAINING OF NDT

TECHNICIANS

Acoustic EmissionAutomation PossibilitiesBlueprint Readinglodes and SpecificationsCombined SystemsComputer SupportEquipment Maintenance and FamiliarizationFactory TrainingField TripsHardness TestingHolographicLegislative Laws and ProposalsMagnetic RubberMicrostructure CorrelationsResponsibility in DetectionSafety Factors and PracticesSensitive Detection MethodsSensitive InstrumentationSet-up ProceduresSignal SynthesisPresent Shortage of NDT TechniciansStandards and SpecificationsSupport from Professional OrganizationsSwinging FieldUpdating EquipmentVibration Analysis

175 167

APPENDIX U

BRANCHES OF INDUSTRY THAT AR" SUPPORTED WITH

NONDESTRUCTIVE TESTING PROCESSES

Aerospace ActivitiesAir Conditioning EquipmentAircraft Manufacturers (complete)Aircraft Manufacturers (parts and sub-assemblies)Aircraft Pilot TrainingAir Force BasesAirlines (freight)Airlines (passenger)Appliance InspectionsArchitecturalArmyArsenalsAutomotive FartsAviation Agencieslond....4 SurfacesBridosCa4tingChemical ProducersCivil EngineeringCompressorsCommunicationsCorrosion ControlDrilling CompaniesElectric CompaniesElectro-mechanicalElectronicsEngine ManufacturersEngineering Testing LaboratoriesFarm EquipmentForging and Rolling MillsGasoline and Oil RefinersGas Transmission CompaniesGeneral EngineeringGeneral ManufactureGround Support Equipment (aircraftlHeat Treating PlantsHeavy ManufacturingHelicopter MaintenanceHelicopter ManufacturersIron and Steel Producers (mills)Leasing Companies

176 168

169

APPENDIX U --Continued

Machinery ProducersMachine ShopsManufacturers (general)Marine ProductsMechanical FabricatorsMedicalMetal ContainersMetal FoundrieFsMetallurgical companiesMetal Parts ManufacturersMetal Shapes FabricatorsMining Equipment ManufacturersMissiles ManufacturersMunitions ManufacturersNational Aeronautics and Space AdministrationNaval Air StationsNondestructive Testing Equipment ManufacturersNonferrous Metal ProducersNuclear Plants PartsOil and Gas IndustriesOrdnance PlantsPipeline InstallationsPlastic ManufacturersPlating PlantsPawer Transmission'Pressure VesselsRailroadsRailroad Parts ManufacturersRefrigerationResearch CentersRoad Machinery ManufacturersScientific Equipment ManufacturersSheet Metal and Fitting3Shipbuilders ard ShipyardsSpace HardwareSteel ProductionTank ManufacturersTool ManufacturersTurbine ManufacturersValves and Related PartsVehicle Manufacturers (passenger)Vehicle Maaufacturers (private)WeaponsWelding Fabricators, Brazed, and Soldered Parts

APPENDIX V

TECHNOLOGIES RECOMMENDED FOR INSTRUCTION

IN NONDESTRUCTIVE TESTING*

TechnologyResponse

Metallurgy 170 85.8Automotive 163 82.3Welding 163 82.3Aerospac.3 160 80.8Bonding 160 80.8Mechanical 158 79.7Machine Shop 152 76.7Refrigeration 152 76.7Electrical 151 76.2Plastics 151 76.2Civil 150 75.7Power Transmission 149 75.2Production 149 75.2Electro-mechanical 148 74.7Sheet Metal 147 74.2Plating 145 73.2Electronic 1 138 69.6

*196 respondents

170

APPENDIX W

NONDESTRUCTIVE TESTING EQUIPMENT

Several items of tezting equipmnt have been selectedfor each of the main areas of nondestructive testing. Theseitems have been recommended by industry and are availablefrom the indicated manufacturers. Because of the detailsinvolved in describing the major item of equipment, no

specifications are 11ted. It is recommended that the manu-facturer be contacted so that brochures can be obtained whichcompletely describe the equipment.

All of the following equipment is not required; however,instructors should choose from those items listed which willserve their training objectives. Also, a great quantity ofequigment is available; therefore, educational personnelshould seek literature from manufacturers prior to requisi-tioning.

179 171

APPENDIX W --Continued

Title

Source

Accessories for Magnaflux

Unit - Model H-710

Contact Pads #1846C pr.

Magnaglo Concentrate No. 14A lb.

Magnaflux

Cost

Type

$39.00

46.50

Magnetic

Particle

Accessories - for Magnatest

Magnaflux

ED 520 Crack Detector

General Purpose Probe P/N 62743

35.00

Ultrasonics

Bolt Hole Probe P/N 204623

(3/16" D.)

65.00

ifta

CO

Accessories - for Ultrasonic

Magnaflux

CD

tester No. PS-702

Model AT-1000 Gate & Attenuation

Correction module P/N 207582

Transducers - straight or

angle beam ea.

375.

00

145.

00

Ultrasonics

Acoustic Emission Plug-in

Nortec

Acoustic

Model NDT-101

1,295.0c

Emission

Cabinet - X-ray fluorescent

W. H. Henken Industries

Radiography

360 Torr unit with redunuant

switch on door

2,400.00

Eddy Current Instrument NDT-8

Nortec

1,145.00

Eddy Current

Conductivity Instrument

Automation Industries, Inc.

Eddy Current

No. EM2100 8-106%

IACS and

26-65% IACS

850.00

_APPENDIX W --Continued

Title

Source

Cost

Type

Conductivity TA,ster -NDT-5

Nortec

$.,95.00

Eddy Current

Conductivity Tester - NDT-5A

Nortec

995.00

Eddy Current

Conductivity Tester -NDT-5-B

Nortec

1,195.00

Eddy Current

Dark Room Tank - and

supplies

Picker Industrial

Radiography

Picker No. 400167

2,150.00

Densitometer - McSeth

Henken Industries

Radiography

Model TD-100A with voltage

regulator

800.00

,.."

Differential Hole Probe

Nortec

95.00

Eddy Current

cri

Differential Surface Probe

Nortec

95.00

Eddy Current

Digital Thickness Instrumsnt

Automation Industries, Inc.

Ultrasonics

G-2 with AMC capabilities

and

3 transducers

53B172

2,000.00

Digital Thickness Instrument

Automation Industries, Inc.

Ultrasonics

G-2S with AMC capabilities and

oscilloscope display and 3

transducers

5313177

4,000.00

Eddy Current Crack Detection -

Nortec

NET 2

695.0C

Eddy Current Crack Detection

with compensation probe and

standard probe No. EM3100

Automation Industries, Inc.

850.00

Eddy Curre

Eddy Curren1

APPENDIX W --Continued

Title

Eddy Current Instrument -

NET-6

Eddy Current - portable

multipurpose No. EM1500 with

frequencies from,1-1000 KH with

frequency modules and probes

Eddy Current Tester

NDT-1 solid state

Eddy Current Tester

NDT-3

00

Film - X-ray and polaroid

film supplies

Frequency Modules -Nortec

Holder -Film No. 545

Polaroid 4 x 5 land

Hole Probe -Eddy Current

Illuminator - High intensity,

Picker No. 240120 with spot

view attachment No. 240121

Source

Nortec

Automation Industries, Inc.

Nortec

Nortec

W. H. Henken Co.

Nortec

Seymour's Photo

Nortec

Gilbert X-ray Co.

Cost

Type

$ 4,999.-00

Eddy Current

850.00

4,750.00

1,995.00

Eddy Current

Eddy Current

Eddy Current

Radiography

1,000.00

25.00

Eddy Current

Radiography

65.00

75.00

Eddy Current

Radiography

APPENDIX W --Continued

Title

Immersion Scanning and Recording

System US454 with tank 18x12z36

inches, turntable and drum for

disc or drum recordings and C

scan.

Complee with mounting

block, search tube and manipula-

tor.

Source

Cost

Type

Automation Industries, Inc.

$10,000.00

Ultrasonics

Isotope CaRera -with source tube, Automation

Industries, Inc.

1,850.00

Radiography

drive beamer and tripod with

clamp (less isotope) Model 520

Inspection Kit - Black light

Instruments - Electrical

measuring pertinent to testing,

inspection and maintenance

activities

Instruments - Metrology

support type, complete kit

Lead Numbers and Letters

Magnaflux Unit - Model

H-710 230V, 60 cyc, 3 phase

with tank and demagnitizaticn

unit and GD-5', Magnaglo Hood

Automation Industries, Inc.

100.00

Liquid

Penetrant

Local

Local

Radiation Equipment Co., Inc,

150.00

Magnaflux

11,530.0G

Radiography

Magnetic

Particle

GO

and thickness

41

APPENDIX W --Continued

Title

Source

Cost

Type

Magnatest - Model ED-520

Magnaflux

$795.00

Ultrasonics

Crack Detector

Magnetic Particle Unit -

Automation IndustriessInc.

950.00

Magnetic

Portable AH-8 with 2 ea.

Particle

15 ft. cables 4/0 and prods

Meter-Survey Victoreen

No. 530924. Model 59213

Picker Industrial

415.00

Radiography

Penetrameter - X-ray reference

Radiation Equipment Co.Ino.

Radiography

blocks, all standard materials

300.00

Penetrant -Fluorscent Dye Kit

Automation Industries,Inc.

150.00

Liquid

Penetrant

Penetrant - Liquid Visible

Automation Industries,Inc.

150.00

Liquid

Dye Kit

Penetrant

Penetrant - Zyglo Kit

Magnaflux

140.00

Liquid

Penetrant

Penetrant Zyglo - ZA28E

Magnaflux

3,290.00

1,iquid

230V, 60 cyc, single phase

Penetrant

inspection black light unit

complete

Probe Cables -Eddy Current

Nortec

15.00

Eddy Current

APPENDIX W --Continued

Title

Source

Cost

Type

Probe - Parker No. 200 Kit

Whitson Engineering Co.,Inc.

$280.00

Magnetic

Particle

Probes - Surface

Nortec

95.00

Eddy Current

Eddy Current

Recorder - Ultrasonic

No. SR5

Krautkramer

2,111.00

Ultrasonics

Sorting Instrument - Eddy

Automation Industries, Inc.

4,500.00

Eddy Current

Current No. EM1300-EM1400

with part ccunter modules

linear time base and flying

spot CRT presentation with

1,2,3 in. I.D. Coils

System - Fluorescent penetrant

Automation Industries, Inc.

all stations and accessories

complete

Tools - Electronic, small

Local

hand for supporting electronic

maintenance activities,

complete kit

Tools - Metal working, small

Local

hand for supporting small metal

working shop, complete kit

Tools, Power, amall pertinent

Local

to electrical and metallur-

gical laboratories

4,000.00

Liquid

Penetrant

Title

Traceable Conductivity

Standards -Eddy Current

Transducers - Ultrasonic

set

Tube - X-ray i6OKV

Headstand complete

65C305

Ultrameter - NDT - 116

Ultrascope - Model NDT-130

Ultrasonic Flaw

Detector Model USK5

Ultrasonic Flaw

Detector Model USK 5) R

Ultrasonic Flaw

Detector Model USK 5M

Ultrasonic Plug-In

Tester - No. NDT-100

APPENDIX W --Continued

Source

Cos

tType

Nortec

$200.00

Eddy Current

Automation Industries, Inc.

1,500.00

Ultrasonics

Automation Industries, Inc.

750.00

Radiography

Nortec

1,500.00

Ultrasonics

Nortec

2,495.00

Ultrasonics

Krautkramer

1,950.00

Ultrasonics

Krautkramer

Krautkramer

Nortec

U3trasonic Tester - Model

Magnaflux

P8-702 Complete with

Transducer Cable, battery pack,

dust cover, cable and manual

2,850.00

U- rasonics

2,350.00

Ultrasonics

695.00

Ultrasonics

2,000.00

Ul).rasonics

APPENDIX W --Continued

Title

Source

Cost

Type

Ultrasonic Tester - Gated

Plug-In Model NDT-102

Nortec

$ 1,295.00

Ultrasonics

Ultrasonic Thickness Tester-

Model NDT-110

Ultrasonic Thickness Gage -

Model NDT-120

Ultrasonic Thickness Gage-'

NDT 120D

Nortec

995.00

Ultrasonics

Nortec

1,145.00

Ultrasonics

Nortec

605.00

Ultraso:zics

4Ultrasonic Underwater

00

Thickness Gage -

.J

Model - 110V

Nortec

1,495.00

Ultrasonics

Ulf asonic Unit - UM771 with

Automation Industries, Inc.

5,500.00

Ultrasonics

AG50D643 AG-1F

50D525 103 db

Pulser-Receiver, 500753

Transigate, 450E641SWB

Recording Amplifier

Ultrasonic Unit - UM775 with

Automation Industries, Inc.

4,000;A

Ultraso.lics

timer AG50D657 and marker

50D571 10W-DAC Pulser-Receiver

Unit - Wet Magnetic Particle

with black light, hood, contact

pads

Automation Industries, Inc.

7,500.00

Magnetic

Particle

Title

X-Ray - Magnaflux Tube Head

150KV, beryllium window

1.5

0,5 mm focal spot

APPENDIX W --Continued

Source

Cost

Type

Mag,

$ 6,000.00

Radiography

X-Ray unit - 160KV, 160-E-8-C,

Automition Industries, Inc.

6,250.00

Radiography

5 ma

40 degrees with beryllium

window, gas filled head

water cooled complet3with:

Power cable 25 ft.

Control cable 25 ft.

Coutrol cable extension 25 ft.

Control cable extension 50 ft.

Coolant hose twin 50 ft.

Power cable 50 ft.

X-Ray unit - Portable

Bendix XM105

Yoke Kit - Portable

Picker Industrial

2,795.00

Radiography

Automation Industries, Inc.

150.00

Magnetic

50B290

Particle

APPENDIX W-1

NUT EQUIPMENT MANUFACTURERS

Automation Industries, Inc.10210 Monroe DriveDallas, Texas 75229

BransonProgress DriveStamford, Conn. 06904

Cenco X-ray4401 W. 26th StreetChicago, Ill. 60623

Custom Machine, Inc.9200 George Ave.Cleveland, Ohio 44105

Dayton X-ray Company1150 W. 2nd StreetDayton, Ohio 45407

DuPont CompanyRoam 7353Wilmingtin, Delaware 19898

Eldorado Manufacturing Co.1935 BriarwoodIrving, Texas

GAF Corporation140 W. 51st StreetNew York, N. Y. 10020

Gilbert X-ray Co.624 Hall St.Dallas, Texas 75226

Industrial RadiographicSupply Unlimited

P. O. Box 746Kenner, La. 70062

JoJrn Enginuering Associat145 lInterprise DriveAnn itrbor, Miehigan 48103

...odak Co.Rochester, N. Y.

189ifil

Krautkramer Ultrasonics, Inc.One Research DriveStratford, Conn. 06497

Magnaflux Corporation6115 Denton DriveDallas, Texas 75235

Nat_ .1 Statham, Inc.92-91 Corona Ave.Elmhurst, N. Y. 11373

Nortec3001 George Washington WayRichland, Washington 99352

Penetrameters20903 So. New Hampshire Ave.Torrance, Calif. 90502

Philips Electronió Instruments750 So Fulton Ave.Mt. Vernon, N. Y. 10550

Picker Industrial1514 Mayfield Ave.Garland, Texas 75040

Radiation Equipment Co.1495 Old Deorfield Rd.Highland Park, Ill. 60035

Seifert X-ray CorporationP. O. Box 124King of Prussia, Pa. 19406

Se7mour's Photo6104 Camp BowieFort Worth, Texas 76116

Tac Instrumentration

"Ir'7t

_.ntoz.;., N. J. 08628

182

APPENDIX W-1 --Continued

Varian611 Hansen WayPalo Alto, Calif. 94303

Victorean Instrument DivisionWoodland Ave.

Cleveland, Ohio 44104

W. H. Henken Industries415 Lillard LaneArlington, Texas

APPENDIX X

LABORATORY ARRANGEMENT

(Floor

lan )

ALiquid Penetrant facilities

BMagnetic Particle facilities

CEddy Current facilities 30

1

A. ,

.. II

I

D Ultrasonic facilities

EBenches for experiments

3 0

Av

APPENDIX X --Continued

LABORATORY ARRANGMENT

(Flo

or P

lan)

A

(tP

ARadiograAlic

BBenches

CDark room

=r1

t

D Radiation testing

ELead shielding, including roof,

for X and gamma ray testin,.,

BIBLIOGRAPHY

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194

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Glasser, O., Physical_ Foundations of Radiology, New York,Paul B. Hoeber, Inc., 196r7-

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Halperin, Don A., walla& With Steel, Chicago, American

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195

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John, D. H. O., Radiographic puanalm in Medicine andIndustry" Evanston, Ill., American Society forNondestructive Testing, 1967.

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